Gemini CLI vs Letta

Gemini CLI 20

Harness reading of the published rubric. No payment protocol (0). Token prices and plan prices are public without a login (20). The 1,000 requests a day Google sign-in tier ended on 18 June 2026. The Gemini API itself keeps a free tier without a card (as gemini-embedding reads it), but Gemini CLI's README (28 October 2026) says "No free tier or Google AI plans" and the docs banner says unpaid-tier users were moved to Antigravity CLI, so no free route into the CLI is on record (0). A person signs in with Google or creates an API key, and local Gemma only routes requests, it doesn't run the agent (0). 0 + 20 + 0 + 0 = 20.

Letta 60

No x402, MPP or L402 (0 of 40). Per-unit API prices are public, $0.10 per active agent a month and $0.00015 a second of tool execution, plus plan prices (20). A $0 plan with bring-your-own keys; no card is mentioned (20). The CLI runs locally without signing in (20). Total 60.

Gemini CLI 90

Apache-2.0 (30). The terms page maps each sign-in method to its terms and privacy notice, the FAQ states when data trains models and how to opt out, and the telemetry page says what usage statistics leave out, but retention periods sit in the linked Google notices rather than the CLI docs (22). Dated deprecation notices exist. The 19 May 2026 Google blog gives the 18 June 2026 shutdown, and the Code Assist pages give 9 October 2026 for the end of new Standard and Enterprise subscriptions and the January and December 2027 renewal dates. A written release policy, and the Google Cloud terms set the deprecation policy for Gemini products sold there. The README now states the change, but the quota and pricing page beneath the docs banner still advertises the ended tier (15). Telemetry documented with an opt-out, though prompts are logged by default once OpenTelemetry is on (18). 30 + 22 + 15 + 18 = 85.

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.

Gemini CLI 67

Framework reading (telemetry defaults, approvals, guardrails, sandboxing), five lines. Usage statistics on by default (privacy.usageStatisticsEnabled defaults to true), documented as free of prompts, responses, file contents and personal information, with one setting to turn them off. Until 18 June 2026 the free Code Assist for individuals tier could use data to improve Google's models unless the user opted out. Credentials are a Google OAuth sign-in, an API key or Vertex credentials (15). Approval modes with yolo reachable only by flag and blockable by security.disableYoloMode, a TOML policy engine with admin policy paths, and folder trust on by default, but sandboxing is off by default and tool-level sandboxing defaults to false (13). Environment-variable redaction, and 0.61.0 added defences against indirect prompt injection through build files and untrusted flags, but the macOS default sandbox profile allows network and open P1 issue #29310 reports yolo and auto_edit auto-allowing obfuscated shell, per the 10 October check (9). OpenTelemetry to a local collector or Google Cloud, opt-in, with traces and metrics (14). SECURITY.md routes reports to g.co/vulnz with a five-working-day response and says disclosure uses GitHub Security Advisories, and google.com has a valid security.txt to 2030. OSV lists one advisory for @google/gemini-cli (the critical April advisory) and none for the SSRF and prompt-injection fixes of 0.59.0 and 0.61.0 (16). SOC 2 isn't scored on the framework reading. 15 + 13 + 9 + 14 + 16 = 67.

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.

Gemini CLI 93

Framework reading. settings.schema.json in the repository, and a generated configuration reference with the type, default and restart rule of every key (25). llms.txt at geminicli.com serving the documentation as Markdown (10). Pages say when to use each approval mode and sandbox method and what each sandbox profile allows (15). Approval modes, sandbox commands and Seatbelt profiles are enums (13). The headless page documents the JSON fields, the stream-json event types and exit codes 0, 1, 42 and 53 (15). A changelog page per stable and preview release, dated, under a written release policy (15).

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.

Gemini CLI 71

Local-package reading. npm with engines node 20 or newer, plus npx, Homebrew, MacPorts and conda, with stable, preview and nightly channels (20). Public CI with ci.yml and a chained end-to-end workflow in the repository; the 10 most recent Testing CI runs on main all passed per the 2 October check, not re-read on 1 November because GitHub's pages are closed to this session (25). 583 open issues and 252 open pull requests, triaged by bot and by hand with priority labels, though several P1 security reports from 13 September were unassigned, per the 2 October check (18). releases.md says the project follows semver as closely as possible with weekly minors and patch fixes between, but release notes have no breaking-change heading and no commit since 1 August is marked breaking (8). 0.66.0, pre-1.0 (0). 20 + 25 + 18 + 8 + 0 = 71.

Letta 58

Local-software lines, read for the harness. @letta-ai/letta-code on npm with Node.js 22.19 or newer, and PyPI wheels for glibc Linux, macOS 14 and Windows x64 with Python 3.9 or newer stated (20). ci.yml, nightly update smoke tests and Telegram live smoke tests exist, but GitHub's API answered with a rate limit, so run results were unread (15 of 25, unchecked). 332 open issues and pull requests, mostly pull requests; recent bug reports such as recall reading the wrong conversation have no reply yet (15 of 25). 398 tags at 0.34.x with release notes on GitHub, no changelog file, and breaking removals such as AgentFile announced in the README (8 of 15). Pre-1.0 (0). Total 58.

Gemini CLI 78

Framework reading, adapted to a harness driven by a pipeline. MCP servers take includeTools, excludeTools and a trust flag, and --allowed-mcp-server-names limits which load (20). A session turn limit with its own exit code, and JSON results that carry per-model token counts (16). Documented exit codes and an error object in JSON output (18). --resume and checkpointing (14). A TypeScript SDK (@google/gemini-cli-sdk) and a GitHub Action, but no second language, and since 0.39.1 a CI run has to set GEMINI_TRUST_WORKSPACE to work in its own checkout (10).

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.