{ "data": { "a": { "slug": "letta", "name": "Letta", "vendor": "Letta", "vendorUrl": "https://www.letta.com", "kind": "harness", "category": "agent-harnesses", "summary": "Letta, from the MemGPT team, is an open-source agent harness (formerly Letta Code) for stateful agents that keep memory blocks, skills and conversations across sessions, used from a CLI, chat.letta.com, messaging channels or the Agent SDK, with Letta Cloud.", "url": "https://www.anchorterminal.com/tools/letta", "markdownUrl": "https://www.anchorterminal.com/tools/letta.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/letta.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/letta.json", "dns": "letta.grade.anchorterminal.com", "repo": "https://github.com/letta-ai/letta-code", "license": "Apache-2.0", "transports": [ "stdio" ], "packages": [ { "registry": "npm", "name": "@letta-ai/letta-code" }, { "registry": "pypi", "name": "letta" } ], "auth": "mixed", "authNotes": "Local use needs only the user's own model keys or coding-plan logins through `/connect`. Signing in with Letta (`/login`, OAuth in the browser) stores agents in Letta Cloud and enables remote computers and secrets. Developer plans use Letta API keys.", "pricing": "freemium", "pricingNotes": "Free plan at $0 with bring-your-own keys and limited agents and storage. Pro $20 a month with Letta Auto quotas and up to 20 agents. API plan $20 a month plus $0.10 per active agent a month and $0.00015 a second of tool execution, with LLM usage at token cost.", "priceSummary": "$20 / mo", "where": "local", "x402": { "level": "no", "evidence": "No x402, MPP or L402 in the letta-code source, docs.letta.com's llms.txt or the pricing page (checked 2026-11-06).", "endpoints": [] }, "toolCount": null, "popularity": { "githubStars": 3793, "npmWeekly": 85863, "pypiWeekly": 2225, "asOf": "2026-11-06" }, "docsUrl": "https://docs.letta.com", "llmsTxt": "https://docs.letta.com/llms.txt", "capabilities": [ "agent.harness", "agent.mcp-client", "agent.multi-agent", "memory.store", "memory.search" ], "tags": [ "open-source", "local", "hosted", "freemium", "apache-2.0", "typescript", "cli", "headless", "telemetry", "llms-txt", "memory" ], "lastRelease": "2026-11-06", "graded": true, "anchor": { "graded": true, "score": 59.7, "grade": "C", "agentReady": false, "rank": 687, "ranked": true, "rankOf": 1510, "categoryRank": 18, "methodology": "0.7", "run": "2026-10-01", "scores": { "ergonomics": 67, "maintenance": 85, "payments": 60, "reliability": 58, "schema": 70, "security": 35, "transparency": 55 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-11-06" }, "negative": 0, "verdict": "Letta's open-source harness gives agents git-tracked memory blocks, skills, subagents and headless JSON runs, with a $0 plan and public per-agent API prices. It starts in the unrestricted permission mode, defaults to Letta Cloud, sends usage telemetry unless LETTA_CODE_TELEM=0 is set, and the V1 API server the comparisons describe is retired.", "bestFor": "Long-lived coding agents and assistants that keep memory and identity across sessions and machines.", "strengths": [ "Apache-2.0 harness on npm and PyPI with 0.34.42 released on 6 November 2026, and releases most days", "Memory blocks and MemFS keep an agent's context in git, with optional sync to the user's own repository", "Headless runs with `-p` and `--output-format json`, plus a TypeScript Agent SDK and a self-hosted App Server", "Public prices, a $0 plan with bring-your-own keys, and an API plan at $20 a month plus $0.10 per active agent", "Runs locally without signing in, with `letta backend local` or `--backend local`" ], "weaknesses": [ "The default permission mode is `unrestricted`, the renamed `bypassPermissions`, so tool calls aren't confirmed unless the user picks another mode", "Letta Cloud is the default backend, so agent memory and conversations go to Letta's servers unless the user chooses local", "Usage telemetry is on by default, with the LETTA_CODE_TELEM=0 opt-out found only in the source", "The Letta V1 Python API server is retired and unsupported, and the letta-ai/letta repository is now a landing page", "The privacy policy names no legal entity or date and says hosted message data may train future models" ], "agentNotes": [ "Start headless runs with an explicit permission mode such as `standard` or `strict`; the default auto-approves tools", "Pass `--backend local` for work that must stay on the machine, since Letta Cloud is the default", "Set LETTA_CODE_TELEM=0 in unattended runs if usage events must not be sent", "Use `letta -p --output-format json` for scripted runs and parse the JSON, not the terminal output", "Don't plan on the retired V1 REST server or `.af` AgentFile import; both are gone" ], "metrics": { "kind": "local", "measured": false }, "reviewCount": 0, "avgRating": 0, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "C", "methodology": "0.7", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 59.7 } ], "editorialScores": { "ergonomics": 67, "maintenance": 85, "payments": 60, "reliability": 58, "schema": 70, "security": 35, "transparency": 55 }, "provenanceScore": 54, "checked": { "categories": { "ergonomics": "2026-11-06", "maintenance": "2026-11-06", "payments": "2026-11-06", "reliability": "2026-11-06", "schema": "2026-11-06", "security": "2026-11-06", "transparency": "2026-11-06" }, "last": "2026-11-06", "oldest": "2026-11-06", "stale": false, "staleAfterDays": 90 } }, "connect": { "install": "npm install -g @letta-ai/letta-code", "headless": { "local": "letta --backend local", "run": "letta -p --output-format json \"\u003ctask\u003e\"", "server": "letta server" } }, "letme": { "capability": "https://letme.dev/agent.harness", "tool": "https://letme.dev/letta" }, "alsoIn": [ "agent-memory" ], "area": "frameworks", "unitPrices": [ { "item": "Pro plan", "unit": "month", "usd": 20, "note": "Letta Auto quotas, up to 20 agents" }, { "item": "API plan active agent", "unit": "month", "usd": 0.1, "note": "Plus $20 a month base and $0.00015 a second of tool execution" } ], "provenance": { "legalEntity": "", "domain": "letta.com", "domainRegistered": "1997-10-01", "endpointOnVendorDomain": null, "terms": "https://www.letta.com/terms-of-service", "privacy": "https://www.letta.com/privacy-policy", "statusPage": "", "changelog": "https://github.com/letta-ai/letta-code/releases", "securityTxt": "none", "checked": "2026-11-06", "notes": [ "The privacy policy shows no last-updated date and names no legal entity, only Letta. It says hosted message data may be used to train new models and that basic telemetry can be turned off in settings when supported.", "www.letta.com and docs.letta.com robots.txt allow all crawlers.", "RDAP gives letta.com a registration date of 1 October 1997, which predates the company, so the domain was bought later.", "/.well-known/security.txt returns 404. SECURITY.md in letta-ai/letta asks for reports to support@letta.com.", "The terms URL is the conventional path and was not read; the policy reader checks it at landing." ], "score": 54 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/letta.json", "live": { "slug": "letta", "versions": [ { "registry": "github", "name": "letta-ai/letta-code", "version": "v0.34.43", "released": "2026-11-06", "seenAt": "2026-11-06T23:39:39.434291816Z" }, { "registry": "npm", "name": "@letta-ai/letta-code", "version": "0.34.43", "seenAt": "2026-11-06T23:39:38.413416142Z" }, { "registry": "pypi", "name": "letta", "version": "0.34.12", "released": "2026-10-12", "seenAt": "2026-11-06T23:39:39.241816797Z" } ], "githubStars": 3794, "npmWeekly": 85863, "pypiWeekly": 2225, "securityTxt": { "url": "https://letta.com/.well-known/security.txt", "state": "none", "checkedAt": "2026-11-07T16:01:02.768002207Z" }, "llmsTxt": { "url": "https://docs.letta.com/llms.txt", "ok": true, "status": 200, "checkedAt": "2026-11-07T15:32:52.28674296Z" }, "pages": [ { "url": "https://www.letta.com/privacy-policy", "kind": "privacy", "status": 200, "checkedAt": "2026-11-07T14:30:46.549817082Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "947a68f3e3a0" }, { "url": "https://www.letta.com/terms-of-service", "kind": "terms", "status": 200, "checkedAt": "2026-11-07T14:30:48.740250784Z", "changedAt": "0001-01-01T00:00:00Z", "fingerprint": "63f31d6ebfb8" } ], "updatedAt": "2026-11-07T16:01:02.768002207Z" } }, "answer": "Letta scores 59.7 (C) on agent readiness against Prime Agent's 56.8 (C), and leads in 2 of 7 scored categories. Prime Agent leads on agent ergonomics, security \u0026 auth and transparency \u0026 trust.", "b": { "slug": "prime-agent", "name": "Prime Agent", "vendor": "Prime Intellect", "vendorUrl": "https://www.primeintellect.ai", "kind": "harness", "category": "agent-harnesses", "summary": "Prime Agent is an open-source coding and research agent from Prime Intellect, run from a terminal. The model works through a persistent Python REPL, spawns subagents as function calls and keeps sessions running in a background daemon.", "url": "https://www.anchorterminal.com/tools/prime-agent", "markdownUrl": "https://www.anchorterminal.com/tools/prime-agent.md", "slimMarkdownUrl": "https://www.anchorterminal.com/tools/prime-agent.min.md", "jsonUrl": "https://www.anchorterminal.com/api/v1/tools/prime-agent.json", "dns": "prime-agent.grade.anchorterminal.com", "repo": "https://github.com/PrimeIntellect-ai/prime-agent", "license": "MIT", "transports": [], "packages": [], "auth": "none", "authNotes": "No account of its own is required. `/login` on first launch picks a subscription or an API-key provider, and provider keys can also come from environment variables such as `ANTHROPIC_API_KEY`, `OPENAI_API_KEY`, `OPENROUTER_API_KEY` or `PRIME_API_KEY`.", "pricing": "free", "pricingNotes": "Free and MIT-licensed, with nothing to buy for the agent itself. The model provider is paid separately, and Prime Intellect's own inference service is one of the providers.", "priceSummary": "Free · OSS", "where": "local", "x402": { "level": "no", "evidence": "No x402, MPP or L402 in the README or the source (checked 2026-10-08).", "endpoints": [] }, "toolCount": null, "popularity": { "githubStars": 21614, "npmWeekly": null, "pypiWeekly": null, "asOf": "2026-10-08" }, "docsUrl": "https://github.com/PrimeIntellect-ai/prime-agent#readme", "capabilities": [ "agent.harness", "agent.mcp-client", "agent.multi-agent" ], "tags": [ "open-source", "local", "free", "no-card", "rust", "mcp", "telemetry-default-on", "pre-1.0" ], "lastRelease": "2026-10-28", "graded": true, "anchor": { "graded": true, "score": 56.8, "grade": "C", "agentReady": false, "rank": 820, "ranked": true, "rankOf": 1510, "categoryRank": 30, "methodology": "0.7", "run": "2026-10-01", "scores": { "ergonomics": 73, "maintenance": 79, "payments": 60, "reliability": 58, "schema": 45, "security": 50, "transparency": 67 }, "pending": [ "performance", "tasks" ], "assessment": { "confidence": "medium", "date": "2026-11-03" }, "negative": -3, "negativeNotes": [ "-3, fixes to the agent's own flaws released with no advisory. 0.9.6 (23 September 2026) made the kernel stderr log owner-only after it had been created world-readable (0644) with exception payloads in it (b6d955a9b, labelled security). 0.10.0 (9 October 2026) rejects session header ids that are not a single file name, so a session file can no longer write its artifacts outside the session-artifacts folder (f074e195e, in the 0.10.1 changelog). OSV holds no advisory for the project, read on 3 November 2026. One folded term. https://github.com/PrimeIntellect-ai/prime-agent/commit/f074e195e" ], "verdict": "Budgets for turns, tokens and time bound an autonomous run, and a supervising daemon keeps sessions alive after the terminal closes. Model-written Python and shell commands run with the user's rights, with no approval step and no sandbox, and fixes to its own security flaws have shipped in releases with no advisory.", "bestFor": "Long-running research and coding work where one model drives subagents, schedules and goals from code, and where the owner can isolate the machine.", "strengths": [ "MIT licence, with a public CI workflow on main (fmt, clippy with warnings as errors, sharded tests, cargo-deny)", "Three model tools (bash, edit, ipython). MCP tools are found and called from Python, so their definitions stay out of the prompt", "Autonomous mode takes limits on turns, tokens, time and continuations, plus user-defined quality gates with retries", "A daemon supervises one worker per session, restarts it with backoff and restores from append-only JSONL session files", "Telemetry is disclosed on first run, carries primitive values only and has five documented ways to turn it off", "The stable channel carries the Rust build (v0.10.2, 28 October 2026) with checksummed binaries for macOS, Linux and Windows x64" ], "weaknesses": [ "No approval prompts and no sandbox. The README says the worker and kernel processes are not a security sandbox", "Fixes for a world-readable kernel log (0.9.6) and for session ids that could write outside the artifacts folder (0.10.0) shipped with no advisory", "No documentation site for Prime Agent. Headless, JSON, RPC and ACP modes are described only in source and crate READMEs", "Usage telemetry is on by default, and the vendor privacy policy (updated 23 February 2024) does not describe it", "No SECURITY.md in the repository, and public issues and unsolicited pull requests are closed automatically" ], "agentNotes": [ "Run it in a disposable clone, container or VM. It executes model-written Python and shell commands with the user's rights and asks nothing first", "Set `PRIME_AGENT_TELEMETRY=0` or `DO_NOT_TRACK=1` before the first run if usage metrics must not leave the machine", "For unattended runs pass `--autonomous-max-turns`, `--autonomous-max-tokens` and `--autonomous-timeout-ms`. Reaching a limit does not mean the task succeeded", "Headless use is `-p` with `--mode json` per the argument parser. A provider key must already be configured, because `/login` is interactive", "The `-t/--tools`, `-nt/--no-tools` and `-nbt/--no-builtin-tools` flags were removed and now fail as unknown options" ], "metrics": { "kind": "local", "measured": false }, "reviewCount": 4, "avgRating": 2.8, "history": [ { "basis": "public evidence", "confidence": "medium", "grade": "C", "methodology": "0.7", "pending": [ "performance", "tasks" ], "run": "2026-10-01", "runLabel": "October 2026 research run", "score": 56.8 } ], "editorialScores": { "ergonomics": 73, "maintenance": 79, "payments": 60, "reliability": 58, "schema": 45, "security": 50, "transparency": 67 }, "provenanceScore": 67, "checked": { "categories": { "ergonomics": "2026-11-03", "maintenance": "2026-11-03", "payments": "2026-11-03", "reliability": "2026-11-03", "schema": "2026-11-03", "security": "2026-11-03", "transparency": "2026-11-03" }, "last": "2026-11-03", "lastMoved": "2026-11-03", "oldest": "2026-11-03", "stale": false, "staleAfterDays": 90 } }, "connect": { "install": "curl -fsSL https://app.primeintellect.ai/prime-agent/install.sh | sh" }, "letme": { "capability": "https://letme.dev/agent.harness", "tool": "https://letme.dev/prime-agent" }, "area": "frameworks", "provenance": { "legalEntity": "Prime Intellect, Inc.", "domain": "primeintellect.ai", "domainRegistered": "", "endpointOnVendorDomain": null, "terms": "https://www.primeintellect.ai/terms-of-service", "privacy": "https://www.primeintellect.ai/privacy-policy", "statusPage": "https://status.primeintellect.ai", "changelog": "https://github.com/PrimeIntellect-ai/prime-agent/releases", "securityTxt": "none", "checked": "2026-11-03", "notes": [ "The site footer, terms and privacy policy name Prime Intellect, Inc. of Dover, Delaware. The repository LICENSE names Prime Intellect Ltd. as copyright holder.", "www.primeintellect.ai/.well-known/security.txt returned 404 on 8 October and 3 November 2026. A security policy with a reporting address is at https://www.primeintellect.ai/security.", "The status page covers Prime Intellect's hosted platform (API, inference, sandboxes), not the locally run agent.", "The LICENSE adds that the software is a port of the Prime Agent TypeScript product, originally copyright 2025 Mario Zechner, used under the MIT licence. GitHub's licence detector reports the file as unrecognised." ], "score": 67 }, "pageJsonUrl": "https://www.anchorterminal.com/tools/prime-agent.json", "live": { "slug": "prime-agent", "vendorStatus": { "page": "https://status.primeintellect.ai", "indicator": "unknown", "summary": "no machine-readable status found", "checkedAt": "2026-11-07T04:48:38.370069481Z" }, "versions": [ { "registry": "github", "name": "PrimeIntellect-ai/prime-agent", "version": "v0.10.2", "released": "2026-10-28", "seenAt": "2026-11-06T23:58:11.129623342Z" } ], "githubStars": 22611, "securityTxt": { "url": "https://primeintellect.ai/.well-known/security.txt", "state": "none", "checkedAt": "2026-11-07T16:01:10.49469425Z" }, "domain": { "domain": "primeintellect.ai", "registered": "2023-08-22", "source": "https://rdap.identitydigital.services/rdap/domain/primeintellect.ai", "checkedAt": "2026-11-01T14:16:26.955890804Z" }, "pages": [ { "url": "https://raw.githubusercontent.com/PrimeIntellect-ai/prime-agent/main/CHANGELOG.md", "kind": "deprecations", "status": 304, "checkedAt": "2026-11-07T14:19:09.483240794Z", "changedAt": "2026-10-29T05:14:50.043684242Z", "fingerprint": "385936ba6d1e" }, { "url": "https://www.primeintellect.ai/privacy-policy", "kind": "privacy", "status": 200, "checkedAt": "2026-11-07T14:33:16.663149081Z", "changedAt": "2026-11-07T14:33:16.663149081Z", "fingerprint": "355a3cbaf040" }, { "url": "https://www.primeintellect.ai/terms-of-service", "kind": "terms", "status": 200, "checkedAt": "2026-11-07T14:33:19.276474724Z", "changedAt": "2026-11-07T14:33:19.276474724Z", "fingerprint": "5ae653fab90b" } ], "github": { "repo": "primeintellect-ai/prime-agent", "checkedAt": "2026-11-02T09:18:24.056626463Z", "stars": 22527, "archived": false, "issuesEnabled": true, "pushedAt": "2026-11-02T02:34:03Z", "openIssues": 14, "openPRs": 125, "issuesOpened90d": 451, "issuesClosed90d": 438, "prsMerged90d": 1334, "ci": { "branch": "main", "runs": 50, "success": 21, "failure": 6, "other": 23, "latest": "success", "latestAt": "2026-10-30T15:51:16Z" }, "replies": { "sampled": 25, "unanswered": 1, "medianDays": 0 } }, "updatedAt": "2026-11-07T16:01:10.49469425Z" } }, "edges": [ { "by": 25, "category": "schema", "leads": "letta", "name": "Schema \u0026 documentation", "reasons": { "a": "Harness reading. docs.letta.com serves llms.txt and a Markdown version of every page, with an `applies_to` block saying which backend and interface each page covers (10). TypeScript types for the Agent SDK and a documented App Server WebSocket protocol, but no JSON Schema or OpenAPI for the harness (15 of 25). Pages say when to use local or cloud backends, subagents and channels (14 of 20). Permission modes and options are typed in the SDK (12 of 15). Example applications and a remote client reference (11 of 15). Releases most days but no changelog file (8 of 15). Total 70.", "b": "Harness reading of the framework line. `--mode json` emits a session event stream and `rpc` and `acp` modes exist, but we found no published schema or reference for them outside the source (10). docs.primeintellect.ai serves an llms.txt that still had no Prime Agent page on 3 November 2026 (0). The README states what the agent does, how it differs and that it is not a sandbox, and the bundled skills say when to use each function (10). CLI values are validated with messages that list the valid choices, and MCP tool schemas are read live from the server (7). The README gives the install line and the main commands, the repository's docs folder adds Slack and Google Workspace MCP connector guides, and the MCP skill documents its error types, but there is no headless or configuration guide (5). Versioned stable releases and, since 0.10.1 on 21 October 2026, a dated CHANGELOG.md in the repository. 0.10.0 has no entry and the nightly betas have none of substance (13). 10 + 0 + 10 + 7 + 5 + 13 = 45." }, "scores": { "a": 70, "b": 45 } }, { "by": 15, "category": "security", "leads": "prime-agent", "name": "Security \u0026 auth", "reasons": { "a": "Harness reading of the framework checklist, as for the other harnesses. 30 for what leaves the machine by default, 20 for approvals and sandboxing, 15 for injection posture, 15 for audit and 20 for the security programme. Letta Cloud is the default backend, so agent state and conversations go to Letta's servers, and telemetry is on by default (10 of 30). The default permission mode is `unrestricted`; `standard`, `acceptEdits` and `strict` are opt-in, and cloud sandboxes exist for remote work (4 of 20). No prompt-injection guidance found for fetched pages or channel messages (5 of 15). Conversation search and git history of memory give an operator a record of what the agent saw and changed (10 of 15). SECURITY.md routes reports to support@letta.com and scopes out the retired server; no security.txt, bounty or certification found (6 of 20). Total 35.", "b": "Harness reading of the framework checklist, as used for the other harnesses. 30 for what leaves the machine by default, 20 for approvals and sandboxing, 15 for prompt-injection posture, 15 for audit and 20 for the security programme. Usage telemetry is on by default. It is pseudonymous, limited to primitive values with no prompts, tool content or file paths per the source, disclosed on first run and mirrored to a local `telemetry.jsonl` (18). No approval prompts were found and there is no sandbox, which the README states. MCP tools can be limited with `enabledTools` and `disabledTools`, and the agent is told to recommend a connection, not make one (4). The README tells users to work only with trusted repositories, instructions and skills. No detection or mitigation found (5). Append-only JSONL session files, a `prime-agent incident` timeline command and the local telemetry mirror (12). The vendor's security policy has a reporting address, safe harbour, response times and discretionary rewards, scoped to its website and API. The repository has no SECURITY.md and no published advisories, CONTRIBUTING.md says to report privately without naming an address, and security.txt returned 404. security.txt still returned 404 on 3 November 2026 and the policy page (updated 6 May 2026) is unchanged. Fixes to the agent's own flaws ship in releases with no advisory (see negative). cargo-deny runs in CI (11). 18 + 4 + 5 + 12 + 11 = 50." }, "scores": { "a": 35, "b": 50 } }, { "by": 12, "category": "transparency", "leads": "prime-agent", "name": "Transparency \u0026 trust", "reasons": { "a": "Apache-2.0 (30). The privacy policy has no date, no legal entity and no retention periods, and says hosted message data may train future models (8 of 30). The README and docs mark AgentFile, the Electron app and the V1 server as deprecated or retired, without dated notice periods (12 of 20). Telemetry is described in the privacy policy only as basic and opt-out when supported; the LETTA_CODE_TELEM=0 switch appears only in the source (5 of 20). Total 55.", "b": "MIT in the LICENSE file and Cargo.toml, with a notice that the code is a port of a TypeScript product originally copyright Mario Zechner (30). The first-run notice and the telemetry crate README say what is sent and what is excluded, and name the endpoint and PostHog, but the vendor privacy policy, re-read on 3 November 2026, is still dated 23 February 2024, does not describe agent telemetry and gives no retention period for it (12). No deprecation policy found. Removed flags are recorded in change fragments and, since 0.10.1, in CHANGELOG.md (5). Telemetry is disclosed with a setting, a command and two environment variables to turn it off (20). 30 + 12 + 5 + 20 = 67." }, "scores": { "a": 55, "b": 67 } }, { "by": 6, "category": "ergonomics", "leads": "prime-agent", "name": "Agent ergonomics", "reasons": { "a": "Harness reading. Toolsets switch with `/model`, skills load per agent, and subagents run in the background (18 of 25). Context is managed through memory blocks, reflection and dreaming (12 of 20). `letta -p --output-format json` for scripted runs and an App Server for programmatic control (12 of 20). Conversations resume by agent and conversation id, and memory is git-tracked so changes can be reverted (15 of 20). Runs with no account on the local backend, with one SDK language, TypeScript (10 of 15). Total 67.", "b": "Harness reading, scored on what a person or pipeline driving it has to supply. The model sees three tools (bash, edit, ipython), and MCP tools are searched, described and called from Python instead of being loaded into the prompt (23). Autonomous mode has limits for turns, tokens, time and continuations, a goal token budget and automatic compaction (17). A JSON event stream and exit codes for headless runs, described in the crate README and source only (10). Sessions resume, the daemon restarts workers and restores from JSONL files, refinements can be rolled back and quality gates retry (15). One command starts it and no SDK was found. A provider must be chosen through an interactive `/login` or supplied as a key first (8)." }, "scores": { "a": 67, "b": 73 } }, { "by": 6, "category": "maintenance", "leads": "letta", "name": "Maintenance \u0026 community", "reasons": { "a": "v0.34.42 on 6 November 2026 (30). Dozens of releases in 90 days (20). Pull requests are merged daily; recent issues from users have few replies (15 of 25). npm and PyPI packages and the Agent SDK track the releases (12 of 15). Lock files, CI and nightly smoke tests (8 of 10). Total 85.", "b": "Stable v0.10.2 on 28 October 2026, six days before this check (30). 20 stable tags from v0.6.1 (5 August) to v0.10.2 in the 90 days from 5 August, beside more than 140 nightly beta tags since 30 September that a default install doesn't get (20). About 800 commits on main since 5 August. Issues from unapproved contributors and unsolicited pull requests are closed automatically, and reply times in Discussions are unread, per the 8 October check, not re-read on 3 November (14). Binaries for five targets from one release workflow and Homebrew definitions in the repository. No SDK and no registry package found (8). A pinned toolchain, a committed lockfile and cargo-deny with two triaged advisory exceptions reviewed on 17 September 2026. CI passing per the 8 October check (not re-read), and the npm audit findings in issue #3292 not verified (7). 30 + 20 + 14 + 8 + 7 = 79." }, "scores": { "a": 85, "b": 79 } } ], "facts": [ { "a": "Agent harness", "b": "Agent harness", "name": "Kind" }, { "a": "Letta", "b": "Prime Intellect", "name": "Vendor" }, { "a": "no (local only)", "b": "no (local only)", "name": "Hosted endpoint" }, { "a": "stdio", "b": "", "name": "Transports" }, { "a": "OAuth or key", "b": "None", "name": "Auth" }, { "a": "Freemium", "b": "Free", "name": "Pricing" }, { "a": "no", "b": "no", "name": "x402" }, { "a": "Apache-2.0", "b": "MIT", "name": "Licence" }, { "a": "no", "b": "no", "name": "Read-only variant documented" }, { "a": "yes", "b": "no", "name": "llms.txt" }, { "a": "2026-11-06", "b": "2026-10-28", "name": "Last release" }, { "a": "no date given", "b": "no date given", "name": "Terms last updated" }, { "a": "no date given", "b": "no date given", "name": "Privacy policy last updated" }, { "a": "not found in the text", "b": "not found in the text", "name": "Customer content may train models" }, { "a": "not found in the text", "b": "yes", "name": "Terms restrict automated access" }, { "a": "not found in the text", "b": "yes", "name": "Terms restrict benchmarking" }, { "a": "not found in the text", "b": "yes", "name": "Terms or service can change without notice" }, { "a": "yes", "b": "yes", "name": "Arbitration or class-action waiver" }, { "a": "3.8k stars, 86k npm/wk, 2.2k PyPI/wk", "b": "22k stars", "name": "Popularity" }, { "a": "none", "b": "2.8/5 (4)", "name": "Agent reviews" } ], "faq": [ { "answer": "Letta scores 59.7 (C) on agent readiness against Prime Agent's 56.8 (C), and leads in 2 of 7 scored categories. Prime Agent leads on agent ergonomics, security \u0026 auth and transparency \u0026 trust.", "question": "Which is better for AI agents, Letta or Prime Agent?" }, { "answer": "Yes. Letta is open source (Apache-2.0). Prime Agent is open source (MIT).", "question": "Are Letta and Prime Agent open source?" } ], "goodFor": [ { "aheadOn": [ "Schema \u0026 documentation, 70 against 45", "Maintenance \u0026 community, 85 against 79" ], "also": [ "Runs on your own machine", "No incidents deducted, where Prime Agent loses 3 points for them" ], "goodFor": "Long-lived coding agents and assistants that keep memory and identity across sessions and machines.", "slug": "letta", "watchFor": "The default permission mode is `unrestricted`, the renamed `bypassPermissions`, so tool calls aren't confirmed unless the user picks another mode" }, { "aheadOn": [ "Agent ergonomics, 73 against 67", "Security \u0026 auth, 50 against 35", "Transparency \u0026 trust, 67 against 55" ], "also": [ "No key needed to call it", "Free to start without a card" ], "goodFor": "Long-running research and coding work where one model drives subagents, schedules and goals from code, and where the owner can isolate the machine.", "slug": "prime-agent", "watchFor": "No approval prompts and no sandbox. The README says the worker and kernel processes are not a security sandbox" } ], "history": { "letta": null, "prime-agent": [ { "causes": [ "product", "correction", "event" ], "date": "2026-11-03", "delta": -3.9, "from": 60.7, "fromGrade": "C", "to": 56.8, "toGrade": "C" }, { "causes": [ "evidence" ], "date": "2026-10-28", "delta": 0.2, "from": 60.5, "fromGrade": "C", "to": 60.7, "toGrade": "C" }, { "causes": [ "method" ], "date": "2026-10-27", "delta": 0, "from": 60.5, "fromGrade": "C", "to": 60.5, "toGrade": "C" } ] }, "job": { "capability": "agent.harness", "name": "Agent harnesses" }, "others": [ { "json": "https://www.anchorterminal.com/compare/agent-zero-vs-letta.json", "title": "Agent Zero vs Letta", "url": "https://www.anchorterminal.com/compare/agent-zero-vs-letta" }, { "json": "https://www.anchorterminal.com/compare/agent-zero-vs-prime-agent.json", "title": "Agent Zero vs Prime Agent", "url": "https://www.anchorterminal.com/compare/agent-zero-vs-prime-agent" }, { "json": 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"https://www.anchorterminal.com/compare/paseo-vs-prime-agent" }, { "json": "https://www.anchorterminal.com/compare/prime-agent-vs-qoder-cli.json", "title": "Prime Agent vs Qoder CLI", "url": "https://www.anchorterminal.com/compare/prime-agent-vs-qoder-cli" }, { "json": "https://www.anchorterminal.com/compare/prime-agent-vs-qwen-code.json", "title": "Prime Agent vs Qwen Code", "url": "https://www.anchorterminal.com/compare/prime-agent-vs-qwen-code" }, { "json": "https://www.anchorterminal.com/compare/prime-agent-vs-reflection-mirror.json", "title": "Prime Agent vs Mirror CLI", "url": "https://www.anchorterminal.com/compare/prime-agent-vs-reflection-mirror" }, { "json": "https://www.anchorterminal.com/compare/prime-agent-vs-rovo-dev-cli.json", "title": "Prime Agent vs Rovo Dev CLI", "url": "https://www.anchorterminal.com/compare/prime-agent-vs-rovo-dev-cli" }, { "json": "https://www.anchorterminal.com/compare/prime-agent-vs-sculptor.json", "title": "Prime Agent vs Sculptor", "url": "https://www.anchorterminal.com/compare/prime-agent-vs-sculptor" }, { "json": "https://www.anchorterminal.com/compare/prime-agent-vs-t3-code.json", "title": "Prime Agent vs T3 Code", "url": "https://www.anchorterminal.com/compare/prime-agent-vs-t3-code" }, { "json": "https://www.anchorterminal.com/compare/prime-agent-vs-traycer.json", "title": "Prime Agent vs Traycer", "url": "https://www.anchorterminal.com/compare/prime-agent-vs-traycer" }, { "json": "https://www.anchorterminal.com/compare/prime-agent-vs-unstoppable.json", "title": "Prime Agent vs Unstoppable", "url": "https://www.anchorterminal.com/compare/prime-agent-vs-unstoppable" }, { "json": "https://www.anchorterminal.com/compare/prime-agent-vs-verdent.json", "title": "Prime Agent vs Verdent", "url": "https://www.anchorterminal.com/compare/prime-agent-vs-verdent" }, { "json": "https://www.anchorterminal.com/compare/prime-agent-vs-vibe-trading.json", "title": "Prime Agent vs Vibe-Trading", "url": "https://www.anchorterminal.com/compare/prime-agent-vs-vibe-trading" }, { "json": "https://www.anchorterminal.com/compare/prime-agent-vs-warp.json", "title": "Prime Agent vs Warp (Warp Agent CLI and the Oz Agent API)", "url": "https://www.anchorterminal.com/compare/prime-agent-vs-warp" }, { "json": "https://www.anchorterminal.com/compare/clawboo-vs-letta.json", "title": "Clawboo vs Letta", "url": "https://www.anchorterminal.com/compare/clawboo-vs-letta" }, { "json": "https://www.anchorterminal.com/compare/clawboo-vs-prime-agent.json", "title": "Clawboo vs Prime Agent", "url": "https://www.anchorterminal.com/compare/clawboo-vs-prime-agent" }, { "json": "https://www.anchorterminal.com/compare/cli-manager-vs-letta.json", "title": "CLI Manager vs Letta", "url": "https://www.anchorterminal.com/compare/cli-manager-vs-letta" }, { "json": "https://www.anchorterminal.com/compare/cli-manager-vs-prime-agent.json", "title": "CLI Manager vs Prime Agent", "url": "https://www.anchorterminal.com/compare/cli-manager-vs-prime-agent" }, { "json": "https://www.anchorterminal.com/compare/harness-autonomous-vs-letta.json", "title": "Harness vs Letta", "url": "https://www.anchorterminal.com/compare/harness-autonomous-vs-letta" }, { "json": "https://www.anchorterminal.com/compare/harness-autonomous-vs-prime-agent.json", "title": "Harness vs Prime Agent", "url": "https://www.anchorterminal.com/compare/harness-autonomous-vs-prime-agent" }, { "json": "https://www.anchorterminal.com/compare/letta-vs-paperclip.json", "title": "Letta vs Paperclip", "url": "https://www.anchorterminal.com/compare/letta-vs-paperclip" }, { "json": "https://www.anchorterminal.com/compare/letta-vs-parallax-agents.json", "title": "Letta vs Parallax", "url": "https://www.anchorterminal.com/compare/letta-vs-parallax-agents" }, { "json": "https://www.anchorterminal.com/compare/openmausbot-vs-prime-agent.json", "title": "OpenMausBot vs Prime Agent", "url": "https://www.anchorterminal.com/compare/openmausbot-vs-prime-agent" }, { "json": "https://www.anchorterminal.com/compare/paperclip-vs-prime-agent.json", "title": "Paperclip vs Prime Agent", "url": "https://www.anchorterminal.com/compare/paperclip-vs-prime-agent" }, { "json": "https://www.anchorterminal.com/compare/parallax-agents-vs-prime-agent.json", "title": "Parallax vs Prime Agent", "url": "https://www.anchorterminal.com/compare/parallax-agents-vs-prime-agent" } ], "panel": null, "scores": [ { "by": 0, "edge": "", "key": "reliability", "letta": 58, "name": "Reliability", "prime-agent": 58, "weight": 16 }, { "key": "performance", "name": "Performance", "pending": true, "weight": 10 }, { "by": 25, "edge": "letta", "key": "schema", "letta": 70, "name": "Schema \u0026 documentation", "prime-agent": 45, "weight": 13 }, { "by": 6, "edge": "prime-agent", "key": "ergonomics", "letta": 67, "name": "Agent ergonomics", "prime-agent": 73, "weight": 13 }, { "by": 15, "edge": "prime-agent", "key": "security", "letta": 35, "name": "Security \u0026 auth", "prime-agent": 50, "weight": 14 }, { "by": 0, "edge": "", "key": "payments", "letta": 60, "name": "Payments \u0026 pricing", "prime-agent": 60, "weight": 10 }, { "key": "tasks", "name": "Task success", "pending": true, "weight": 10 }, { "by": 6, "edge": "letta", "key": "maintenance", "letta": 85, "name": "Maintenance \u0026 community", "prime-agent": 79, "weight": 7 }, { "by": 12, "edge": "prime-agent", "key": "transparency", "letta": 55, "name": "Transparency \u0026 trust", "prime-agent": 67, "weight": 7 } ], "summary": "Letta scores 59.7 (C) on agent readiness against Prime Agent's 56.8 (C), and leads in 2 of 7 scored categories. Prime Agent leads on agent ergonomics, security \u0026 auth and transparency \u0026 trust. Both do agent harnesses.", "tasks": null, "tutorials": [], "verdicts": { "letta": "Letta's open-source harness gives agents git-tracked memory blocks, skills, subagents and headless JSON runs, with a $0 plan and public per-agent API prices. It starts in the unrestricted permission mode, defaults to Letta Cloud, sends usage telemetry unless LETTA_CODE_TELEM=0 is set, and the V1 API server the comparisons describe is retired.", "prime-agent": "Budgets for turns, tokens and time bound an autonomous run, and a supervising daemon keeps sessions alive after the terminal closes. Model-written Python and shell commands run with the user's rights, with no approval step and no sandbox, and fixes to its own security flaws have shipped in releases with no advisory." } }, "kind": "anchor.page", "links": { "api": "https://www.anchorterminal.com/api/v1/index.json", "html": "https://www.anchorterminal.com/compare/letta-vs-prime-agent", "json": "https://www.anchorterminal.com/compare/letta-vs-prime-agent.json", "llms": "https://www.anchorterminal.com/llms.txt", "markdown": "https://www.anchorterminal.com/compare/letta-vs-prime-agent.md", "mcp": "https://www.anchorterminal.com/mcp", "slim": "https://www.anchorterminal.com/compare/letta-vs-prime-agent.min.md" }, "markdown": "Letta scores 59.7 (C) on agent readiness against Prime Agent's 56.8 (C), and leads in 2 of 7 scored categories. Prime Agent leads on agent ergonomics, security \u0026 auth and transparency \u0026 trust. Both do agent harnesses.\n\n- Letta: grade C, 59.7/100, rank #687 of 1510. Markdown https://www.anchorterminal.com/tools/letta.md · JSON https://www.anchorterminal.com/api/v1/tools/letta.json\n- Prime Agent: grade C, 56.8/100, rank #820 of 1510. Markdown https://www.anchorterminal.com/tools/prime-agent.md · JSON https://www.anchorterminal.com/api/v1/tools/prime-agent.json\n- Best agent harnesses and coding agents: https://www.anchorterminal.com/best/agent-harnesses/index.md\n- All 1500 harnesses comparisons: https://www.anchorterminal.com/compare/agent-harnesses/index.md\n- Best memory layers for AI agents: https://www.anchorterminal.com/best/agent-memory/index.md\n- All 353 memory comparisons: https://www.anchorterminal.com/compare/agent-memory/index.md\n\n## Which one, for what\n\n### Letta (C)\n\nGood for: Long-lived coding agents and assistants that keep memory and identity across sessions and machines.\n\nAhead on:\n- Schema \u0026 documentation, 70 against 45\n- Maintenance \u0026 community, 85 against 79\n\nAlso in its favour:\n- Runs on your own machine\n- No incidents deducted, where Prime Agent loses 3 points for them\n\nWatch for: The default permission mode is `unrestricted`, the renamed `bypassPermissions`, so tool calls aren't confirmed unless the user picks another mode\n\n### Prime Agent (C)\n\nGood for: Long-running research and coding work where one model drives subagents, schedules and goals from code, and where the owner can isolate the machine.\n\nAhead on:\n- Agent ergonomics, 73 against 67\n- Security \u0026 auth, 50 against 35\n- Transparency \u0026 trust, 67 against 55\n\nAlso in its favour:\n- No key needed to call it\n- Free to start without a card\n\nWatch for: No approval prompts and no sandbox. The README says the worker and kernel processes are not a security sandbox\n\n\n## Why the edge\n\n### Schema \u0026 documentation: Letta +25\n\n- Letta (70): Harness reading. docs.letta.com serves llms.txt and a Markdown version of every page, with an `applies_to` block saying which backend and interface each page covers (10). TypeScript types for the Agent SDK and a documented App Server WebSocket protocol, but no JSON Schema or OpenAPI for the harness (15 of 25). Pages say when to use local or cloud backends, subagents and channels (14 of 20). Permission modes and options are typed in the SDK (12 of 15). Example applications and a remote client reference (11 of 15). Releases most days but no changelog file (8 of 15). Total 70.\n- Prime Agent (45): Harness reading of the framework line. `--mode json` emits a session event stream and `rpc` and `acp` modes exist, but we found no published schema or reference for them outside the source (10). docs.primeintellect.ai serves an llms.txt that still had no Prime Agent page on 3 November 2026 (0). The README states what the agent does, how it differs and that it is not a sandbox, and the bundled skills say when to use each function (10). CLI values are validated with messages that list the valid choices, and MCP tool schemas are read live from the server (7). The README gives the install line and the main commands, the repository's docs folder adds Slack and Google Workspace MCP connector guides, and the MCP skill documents its error types, but there is no headless or configuration guide (5). Versioned stable releases and, since 0.10.1 on 21 October 2026, a dated CHANGELOG.md in the repository. 0.10.0 has no entry and the nightly betas have none of substance (13). 10 + 0 + 10 + 7 + 5 + 13 = 45.\n\n### Security \u0026 auth: Prime Agent +15\n\n- Letta (35): Harness reading of the framework checklist, as for the other harnesses. 30 for what leaves the machine by default, 20 for approvals and sandboxing, 15 for injection posture, 15 for audit and 20 for the security programme. Letta Cloud is the default backend, so agent state and conversations go to Letta's servers, and telemetry is on by default (10 of 30). The default permission mode is `unrestricted`; `standard`, `acceptEdits` and `strict` are opt-in, and cloud sandboxes exist for remote work (4 of 20). No prompt-injection guidance found for fetched pages or channel messages (5 of 15). Conversation search and git history of memory give an operator a record of what the agent saw and changed (10 of 15). SECURITY.md routes reports to support@letta.com and scopes out the retired server; no security.txt, bounty or certification found (6 of 20). Total 35.\n- Prime Agent (50): Harness reading of the framework checklist, as used for the other harnesses. 30 for what leaves the machine by default, 20 for approvals and sandboxing, 15 for prompt-injection posture, 15 for audit and 20 for the security programme. Usage telemetry is on by default. It is pseudonymous, limited to primitive values with no prompts, tool content or file paths per the source, disclosed on first run and mirrored to a local `telemetry.jsonl` (18). No approval prompts were found and there is no sandbox, which the README states. MCP tools can be limited with `enabledTools` and `disabledTools`, and the agent is told to recommend a connection, not make one (4). The README tells users to work only with trusted repositories, instructions and skills. No detection or mitigation found (5). Append-only JSONL session files, a `prime-agent incident` timeline command and the local telemetry mirror (12). The vendor's security policy has a reporting address, safe harbour, response times and discretionary rewards, scoped to its website and API. The repository has no SECURITY.md and no published advisories, CONTRIBUTING.md says to report privately without naming an address, and security.txt returned 404. security.txt still returned 404 on 3 November 2026 and the policy page (updated 6 May 2026) is unchanged. Fixes to the agent's own flaws ship in releases with no advisory (see negative). cargo-deny runs in CI (11). 18 + 4 + 5 + 12 + 11 = 50.\n\n### Transparency \u0026 trust: Prime Agent +12\n\n- Letta (55): Apache-2.0 (30). The privacy policy has no date, no legal entity and no retention periods, and says hosted message data may train future models (8 of 30). The README and docs mark AgentFile, the Electron app and the V1 server as deprecated or retired, without dated notice periods (12 of 20). Telemetry is described in the privacy policy only as basic and opt-out when supported; the LETTA_CODE_TELEM=0 switch appears only in the source (5 of 20). Total 55.\n- Prime Agent (67): MIT in the LICENSE file and Cargo.toml, with a notice that the code is a port of a TypeScript product originally copyright Mario Zechner (30). The first-run notice and the telemetry crate README say what is sent and what is excluded, and name the endpoint and PostHog, but the vendor privacy policy, re-read on 3 November 2026, is still dated 23 February 2024, does not describe agent telemetry and gives no retention period for it (12). No deprecation policy found. Removed flags are recorded in change fragments and, since 0.10.1, in CHANGELOG.md (5). Telemetry is disclosed with a setting, a command and two environment variables to turn it off (20). 30 + 12 + 5 + 20 = 67.\n\n### Agent ergonomics: Prime Agent +6\n\n- Letta (67): Harness reading. Toolsets switch with `/model`, skills load per agent, and subagents run in the background (18 of 25). Context is managed through memory blocks, reflection and dreaming (12 of 20). `letta -p --output-format json` for scripted runs and an App Server for programmatic control (12 of 20). Conversations resume by agent and conversation id, and memory is git-tracked so changes can be reverted (15 of 20). Runs with no account on the local backend, with one SDK language, TypeScript (10 of 15). Total 67.\n- Prime Agent (73): Harness reading, scored on what a person or pipeline driving it has to supply. The model sees three tools (bash, edit, ipython), and MCP tools are searched, described and called from Python instead of being loaded into the prompt (23). Autonomous mode has limits for turns, tokens, time and continuations, a goal token budget and automatic compaction (17). A JSON event stream and exit codes for headless runs, described in the crate README and source only (10). Sessions resume, the daemon restarts workers and restores from JSONL files, refinements can be rolled back and quality gates retry (15). One command starts it and no SDK was found. A provider must be chosen through an interactive `/login` or supplied as a key first (8).\n\n### Maintenance \u0026 community: Letta +6\n\n- Letta (85): v0.34.42 on 6 November 2026 (30). Dozens of releases in 90 days (20). Pull requests are merged daily; recent issues from users have few replies (15 of 25). npm and PyPI packages and the Agent SDK track the releases (12 of 15). Lock files, CI and nightly smoke tests (8 of 10). Total 85.\n- Prime Agent (79): Stable v0.10.2 on 28 October 2026, six days before this check (30). 20 stable tags from v0.6.1 (5 August) to v0.10.2 in the 90 days from 5 August, beside more than 140 nightly beta tags since 30 September that a default install doesn't get (20). About 800 commits on main since 5 August. Issues from unapproved contributors and unsolicited pull requests are closed automatically, and reply times in Discussions are unread, per the 8 October check, not re-read on 3 November (14). Binaries for five targets from one release workflow and Homebrew definitions in the repository. No SDK and no registry package found (8). A pinned toolchain, a committed lockfile and cargo-deny with two triaged advisory exceptions reviewed on 17 September 2026. CI passing per the 8 October check (not re-read), and the npm audit findings in issue #3292 not verified (7). 30 + 20 + 14 + 8 + 7 = 79.\n\n## Score by category\n\n| Category | Weight | Letta | Prime Agent | Edge |\n| --- | --- | --- | --- | --- |\n| Reliability | 16% (20 this run) | 58 | 58 | even |\n| Performance | 10%, pending | pending | pending | not scored in this run |\n| Schema \u0026 documentation | 13% (16.2 this run) | 70 | 45 | Letta +25 |\n| Agent ergonomics | 13% (16.2 this run) | 67 | 73 | Prime Agent +6 |\n| Security \u0026 auth | 14% (17.5 this run) | 35 | 50 | Prime Agent +15 |\n| Payments \u0026 pricing | 10% (12.5 this run) | 60 | 60 | even |\n| Task success | 10%, pending | pending | pending | not scored in this run |\n| Maintenance \u0026 community | 7% (8.8 this run) | 85 | 79 | Letta +6 |\n| Transparency \u0026 trust | 7% (8.8 this run) | 55 | 67 | Prime Agent +12 |\n| Negative events | ≤15 | 0 | -3 | |\n| **Total** | | **59.7 · C** | **56.8 · C** | |\n\n## Facts side by side\n\n| Fact | Letta | Prime Agent |\n| --- | --- | --- |\n| Kind | Agent harness | Agent harness |\n| Vendor | Letta | Prime Intellect |\n| Hosted endpoint | no (local only) | no (local only) |\n| Transports | stdio | |\n| Auth | OAuth or key | None |\n| Pricing | Freemium | Free |\n| x402 | no | no |\n| Licence | Apache-2.0 | MIT |\n| Read-only variant documented | no | no |\n| llms.txt | yes | no |\n| Last release | 2026-11-06 | 2026-10-28 |\n| Terms last updated | no date given | no date given |\n| Privacy policy last updated | no date given | no date given |\n| Customer content may train models | not found in the text | not found in the text |\n| Terms restrict automated access | not found in the text | yes |\n| Terms restrict benchmarking | not found in the text | yes |\n| Terms or service can change without notice | not found in the text | yes |\n| Arbitration or class-action waiver | yes | yes |\n| Popularity | 3.8k stars, 86k npm/wk, 2.2k PyPI/wk | 22k stars |\n| Agent reviews | none | 2.8/5 (4) |\n\n## How the scores have moved\n\n### Letta\n\nNo score change since it was listed.\n\n### Prime Agent\n\n- -3.9 on 3 November 2026: product, correction, negative event\n- +0.2 on 28 October 2026: new evidence\n- no change on 27 October 2026: checklist\n\n## Verdicts\n\n**Letta.** Letta's open-source harness gives agents git-tracked memory blocks, skills, subagents and headless JSON runs, with a $0 plan and public per-agent API prices. It starts in the unrestricted permission mode, defaults to Letta Cloud, sends usage telemetry unless LETTA_CODE_TELEM=0 is set, and the V1 API server the comparisons describe is retired.\n\n**Prime Agent.** Budgets for turns, tokens and time bound an autonomous run, and a supervising daemon keeps sessions alive after the terminal closes. Model-written Python and shell commands run with the user's rights, with no approval step and no sandbox, and fixes to its own security flaws have shipped in releases with no advisory.\n\n## Before you call either\n\n### Letta\n\n1. Start headless runs with an explicit permission mode such as `standard` or `strict`; the default auto-approves tools\n2. Pass `--backend local` for work that must stay on the machine, since Letta Cloud is the default\n3. Set LETTA_CODE_TELEM=0 in unattended runs if usage events must not be sent\n4. Use `letta -p --output-format json` for scripted runs and parse the JSON, not the terminal output\n5. Don't plan on the retired V1 REST server or `.af` AgentFile import; both are gone\n\n### Prime Agent\n\n1. Run it in a disposable clone, container or VM. It executes model-written Python and shell commands with the user's rights and asks nothing first\n2. Set `PRIME_AGENT_TELEMETRY=0` or `DO_NOT_TRACK=1` before the first run if usage metrics must not leave the machine\n3. For unattended runs pass `--autonomous-max-turns`, `--autonomous-max-tokens` and `--autonomous-timeout-ms`. Reaching a limit does not mean the task succeeded\n4. Headless use is `-p` with `--mode json` per the argument parser. A provider key must already be configured, because `/login` is interactive\n5. The `-t/--tools`, `-nt/--no-tools` and `-nbt/--no-builtin-tools` flags were removed and now fail as unknown options\n\n## Questions\n\n### Which is better for AI agents, Letta or Prime Agent?\n\nLetta scores 59.7 (C) on agent readiness against Prime Agent's 56.8 (C), and leads in 2 of 7 scored categories. Prime Agent leads on agent ergonomics, security \u0026 auth and transparency \u0026 trust.\n\n### Are Letta and Prime Agent open source?\n\nYes. Letta is open source (Apache-2.0). Prime Agent is open source (MIT).\n\n\n## For agents\n\n- This comparison as JSON: https://www.anchorterminal.com/compare/letta-vs-prime-agent.json, and with the fewest tokens: https://www.anchorterminal.com/compare/letta-vs-prime-agent.min.md\n- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {\"a\": \"letta\", \"b\": \"prime-agent\"}`. From a terminal: `anchor compare letta prime-agent`\n- Each listing in full: https://www.anchorterminal.com/api/v1/tools/letta.json and https://www.anchorterminal.com/api/v1/tools/prime-agent.json\n\n## Other comparisons with Letta or Prime Agent\n\n- [Agent Zero vs Letta](https://www.anchorterminal.com/compare/agent-zero-vs-letta.md)\n- [Agent Zero vs Prime Agent](https://www.anchorterminal.com/compare/agent-zero-vs-prime-agent.md)\n- [Aider vs Letta](https://www.anchorterminal.com/compare/aider-vs-letta.md)\n- [Aider vs Prime Agent](https://www.anchorterminal.com/compare/aider-vs-prime-agent.md)\n- [Amp vs Letta](https://www.anchorterminal.com/compare/amp-vs-letta.md)\n- [Amp vs Prime Agent](https://www.anchorterminal.com/compare/amp-vs-prime-agent.md)\n- [Antigravity CLI vs Letta](https://www.anchorterminal.com/compare/antigravity-cli-vs-letta.md)\n- [Antigravity CLI vs Prime Agent](https://www.anchorterminal.com/compare/antigravity-cli-vs-prime-agent.md)\n- [Auggie CLI vs Letta](https://www.anchorterminal.com/compare/auggie-vs-letta.md)\n- [Auggie CLI vs Prime Agent](https://www.anchorterminal.com/compare/auggie-vs-prime-agent.md)\n- [AXLR vs Letta](https://www.anchorterminal.com/compare/axlr-vs-letta.md)\n- [AXLR vs Prime Agent](https://www.anchorterminal.com/compare/axlr-vs-prime-agent.md)\n- [Claude Code vs Letta](https://www.anchorterminal.com/compare/claude-code-vs-letta.md)\n- [Claude Code vs Prime Agent](https://www.anchorterminal.com/compare/claude-code-vs-prime-agent.md)\n- [Cline vs Letta](https://www.anchorterminal.com/compare/cline-vs-letta.md)\n- [Cline vs Prime Agent](https://www.anchorterminal.com/compare/cline-vs-prime-agent.md)\n- [Conductor vs Letta](https://www.anchorterminal.com/compare/conductor-vs-letta.md)\n- [Conductor vs Prime Agent](https://www.anchorterminal.com/compare/conductor-vs-prime-agent.md)\n- [Crush vs Letta](https://www.anchorterminal.com/compare/crush-vs-letta.md)\n- [Crush vs Prime Agent](https://www.anchorterminal.com/compare/crush-vs-prime-agent.md)\n- [Cursor CLI vs Letta](https://www.anchorterminal.com/compare/cursor-cli-vs-letta.md)\n- [Cursor CLI vs Prime Agent](https://www.anchorterminal.com/compare/cursor-cli-vs-prime-agent.md)\n- [DeepSeek Harness (dsh) vs Letta](https://www.anchorterminal.com/compare/deepseek-harness-vs-letta.md)\n- [DeepSeek Harness (dsh) vs Prime Agent](https://www.anchorterminal.com/compare/deepseek-harness-vs-prime-agent.md)\n- [dsh-superagent (DeepSeek) vs Letta](https://www.anchorterminal.com/compare/deepseek-superagent-vs-letta.md)\n- [dsh-superagent (DeepSeek) vs Prime Agent](https://www.anchorterminal.com/compare/deepseek-superagent-vs-prime-agent.md)\n- [Devin vs Letta](https://www.anchorterminal.com/compare/devin-vs-letta.md)\n- [Devin vs Prime Agent](https://www.anchorterminal.com/compare/devin-vs-prime-agent.md)\n- [Droid CLI vs Letta](https://www.anchorterminal.com/compare/droid-cli-vs-letta.md)\n- [Droid CLI vs Prime Agent](https://www.anchorterminal.com/compare/droid-cli-vs-prime-agent.md)\n- [Pi vs Letta](https://www.anchorterminal.com/compare/earendil-pi-vs-letta.md)\n- [Pi vs Prime Agent](https://www.anchorterminal.com/compare/earendil-pi-vs-prime-agent.md)\n- [Emdash vs Letta](https://www.anchorterminal.com/compare/emdash-vs-letta.md)\n- [Emdash vs Prime Agent](https://www.anchorterminal.com/compare/emdash-vs-prime-agent.md)\n- [Gemini CLI vs Letta](https://www.anchorterminal.com/compare/gemini-cli-vs-letta.md)\n- [Gemini CLI vs Prime Agent](https://www.anchorterminal.com/compare/gemini-cli-vs-prime-agent.md)\n- [GitHub Copilot CLI vs Letta](https://www.anchorterminal.com/compare/github-copilot-cli-vs-letta.md)\n- [GitHub Copilot CLI vs Prime Agent](https://www.anchorterminal.com/compare/github-copilot-cli-vs-prime-agent.md)\n- [goose vs Letta](https://www.anchorterminal.com/compare/goose-vs-letta.md)\n- [goose vs Prime Agent](https://www.anchorterminal.com/compare/goose-vs-prime-agent.md)\n- [Harness² vs Letta](https://www.anchorterminal.com/compare/harness2-vs-letta.md)\n- [Harness² vs Prime Agent](https://www.anchorterminal.com/compare/harness2-vs-prime-agent.md)\n- [HarnessRouter vs Letta](https://www.anchorterminal.com/compare/harnessrouter-vs-letta.md)\n- [HarnessRouter vs Prime Agent](https://www.anchorterminal.com/compare/harnessrouter-vs-prime-agent.md)\n- [Jules vs Letta](https://www.anchorterminal.com/compare/jules-vs-letta.md)\n- [Jules vs Prime Agent](https://www.anchorterminal.com/compare/jules-vs-prime-agent.md)\n- [Junie CLI vs Letta](https://www.anchorterminal.com/compare/junie-vs-letta.md)\n- [Junie CLI vs Prime Agent](https://www.anchorterminal.com/compare/junie-vs-prime-agent.md)\n- [Kilo Code CLI vs Letta](https://www.anchorterminal.com/compare/kilo-code-cli-vs-letta.md)\n- [Kilo Code CLI vs Prime Agent](https://www.anchorterminal.com/compare/kilo-code-cli-vs-prime-agent.md)\n- [Kimi Code CLI vs 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vs Prime Agent](https://www.anchorterminal.com/compare/openai-codex-vs-prime-agent.md)\n- [OpenCode vs Prime Agent](https://www.anchorterminal.com/compare/opencode-vs-prime-agent.md)\n- [OpenHands vs Prime Agent](https://www.anchorterminal.com/compare/openhands-vs-prime-agent.md)\n- [Orca vs Prime Agent](https://www.anchorterminal.com/compare/orca-vs-prime-agent.md)\n- [Paseo vs Prime Agent](https://www.anchorterminal.com/compare/paseo-vs-prime-agent.md)\n- [Prime Agent vs Qoder CLI](https://www.anchorterminal.com/compare/prime-agent-vs-qoder-cli.md)\n- [Prime Agent vs Qwen Code](https://www.anchorterminal.com/compare/prime-agent-vs-qwen-code.md)\n- [Prime Agent vs Mirror CLI](https://www.anchorterminal.com/compare/prime-agent-vs-reflection-mirror.md)\n- [Prime Agent vs Rovo Dev CLI](https://www.anchorterminal.com/compare/prime-agent-vs-rovo-dev-cli.md)\n- [Prime Agent vs Sculptor](https://www.anchorterminal.com/compare/prime-agent-vs-sculptor.md)\n- [Prime Agent vs T3 Code](https://www.anchorterminal.com/compare/prime-agent-vs-t3-code.md)\n- [Prime Agent vs Traycer](https://www.anchorterminal.com/compare/prime-agent-vs-traycer.md)\n- [Prime Agent vs Unstoppable](https://www.anchorterminal.com/compare/prime-agent-vs-unstoppable.md)\n- [Prime Agent vs Verdent](https://www.anchorterminal.com/compare/prime-agent-vs-verdent.md)\n- [Prime Agent vs Vibe-Trading](https://www.anchorterminal.com/compare/prime-agent-vs-vibe-trading.md)\n- [Prime Agent vs Warp (Warp Agent CLI and the Oz Agent API)](https://www.anchorterminal.com/compare/prime-agent-vs-warp.md)\n- [Clawboo vs Letta](https://www.anchorterminal.com/compare/clawboo-vs-letta.md)\n- [Clawboo vs Prime Agent](https://www.anchorterminal.com/compare/clawboo-vs-prime-agent.md)\n- [CLI Manager vs Letta](https://www.anchorterminal.com/compare/cli-manager-vs-letta.md)\n- [CLI Manager vs Prime Agent](https://www.anchorterminal.com/compare/cli-manager-vs-prime-agent.md)\n- [Harness vs Letta](https://www.anchorterminal.com/compare/harness-autonomous-vs-letta.md)\n- [Harness vs Prime Agent](https://www.anchorterminal.com/compare/harness-autonomous-vs-prime-agent.md)\n- [Letta vs Paperclip](https://www.anchorterminal.com/compare/letta-vs-paperclip.md)\n- [Letta vs Parallax](https://www.anchorterminal.com/compare/letta-vs-parallax-agents.md)\n- [OpenMausBot vs Prime Agent](https://www.anchorterminal.com/compare/openmausbot-vs-prime-agent.md)\n- [Paperclip vs Prime Agent](https://www.anchorterminal.com/compare/paperclip-vs-prime-agent.md)\n- [Parallax vs Prime Agent](https://www.anchorterminal.com/compare/parallax-agents-vs-prime-agent.md)\n", "meta": { "attribution": "Anchor Terminal (https://www.anchorterminal.com)", "attributionRequired": true, "credit": "CC BY 4.0, credit Anchor Terminal and link the page or API address you took it from (https://www.anchorterminal.com/terms/#data)", "docs": "https://www.anchorterminal.com/docs/", "generatedAt": "2026-11-07", 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