# Letta vs Sculptor

> Letta scores 59.7 (C) to Sculptor's 53.1 (D) for agent harnesses. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/letta-vs-sculptor
- Markdown: https://www.anchorterminal.com/compare/letta-vs-sculptor.md (~5,200 tokens)
- Site index for agents: https://www.anchorterminal.com/llms.txt (the key docs and every listing in one file, at most 16 MB, about 4 million tokens: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- MCP: https://www.anchorterminal.com/mcp (the whole catalogue as tools, no key)
- DNS: dig +short TXT <slug>.grade.anchorterminal.com (the grade as a DNS TXT record, for a sandbox with no HTTP where names still resolve; also top., best.<category>. and <a>.vs.<b>. under the zone, and the same under grade.letme.dev)
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)
- Updated: 2026-11-07

Letta scores 59.7 (C) on agent readiness against Sculptor's 53.1 (D), and leads in 4 of 7 scored categories. Sculptor leads on security & auth. Both do agent harnesses.

- 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
- Sculptor: grade D, 53.1/100, rank #966 of 1510. Markdown https://www.anchorterminal.com/tools/sculptor.md · JSON https://www.anchorterminal.com/api/v1/tools/sculptor.json
- Best agent harnesses and coding agents: https://www.anchorterminal.com/best/agent-harnesses/index.md
- All 1500 harnesses comparisons: https://www.anchorterminal.com/compare/agent-harnesses/index.md
- Best memory layers for AI agents: https://www.anchorterminal.com/best/agent-memory/index.md
- All 353 memory comparisons: https://www.anchorterminal.com/compare/agent-memory/index.md

## Which one, for what

### Letta (C)

Good for: Long-lived coding agents and assistants that keep memory and identity across sessions and machines.

Ahead on:
- Reliability, 58 against 43
- Schema & documentation, 70 against 45
- Agent ergonomics, 67 against 50
- Maintenance & community, 85 against 75

Also in its favour:
- Runs on your own machine

Watch for: The default permission mode is `unrestricted`, the renamed `bypassPermissions`, so tool calls aren't confirmed unless the user picks another mode

### Sculptor (D)

Good for: Developers who want parallel coding agents in isolated workspaces and are fine with a research preview.

Ahead on:
- Security & auth, 57 against 35

Also in its favour:
- No key needed to call it

Watch for: Labelled an experimental research preview that may change drastically


## Why the edge

### Schema & documentation: Letta +25

- 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.
- Sculptor (45): Harness reading. A README, specs and agent docs in the repository; no API reference (45).

### Security & auth: Sculptor +22

- 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.
- Sculptor (57): Harness reading. Product analytics, error reporting and session recording default to off in the user config, and the app asks for a telemetry level and privacy consent at first run; PostHog runs on the front end only for now (25 of 30). Each workspace is an isolated copy of the code (14 of 20). No prompt-injection guidance (5). No audit log (5). SECURITY.md (8). 25 + 14 + 5 + 5 + 8 = 57.

### Agent ergonomics: Letta +17

- 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.
- Sculptor (50): Harness reading. Workspaces as isolated copies, review and merge back, and built-in skills (50).

### Reliability: Letta +15

- 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.
- Sculptor (43): Local software. Desktop downloads for Mac (Apple Silicon), Linux and Linux ARM64 (20). checks.yml and a PR gate run on the repository; pass state not read (15). GitHub issues and pull requests weren't read (GitHub's pages refuse these sessions), so that line is scored absent (0). sculptor-v tags up to v0.49.0, no changelog file (8). 0.x and labelled a research preview (0). 20 + 15 + 0 + 8 + 0 = 43.

### Maintenance & community: Letta +10

- 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.
- Sculptor (75): Commits on 6 November 2026 and frequent tagged versions (30). More than three releases in 90 days (20). GitHub issues and pull requests weren't read (GitHub's pages refuse these sessions), so that line is scored absent; the README says Imbue can't take many outside contributions yet (0). Current official downloads (15). CI on pull requests (10). 30 + 20 + 0 + 15 + 10 = 75.

## Score by category

| Category | Weight | Letta | Sculptor | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 58 | 43 | Letta +15 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 70 | 45 | Letta +25 |
| Agent ergonomics | 13% (16.2 this run) | 67 | 50 | Letta +17 |
| Security & auth | 14% (17.5 this run) | 35 | 57 | Sculptor +22 |
| Payments & pricing | 10% (12.5 this run) | 60 | 60 | even |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 85 | 75 | Letta +10 |
| Transparency & trust | 7% (8.8 this run) | 55 | 57 | Sculptor +2 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **59.7 · C** | **53.1 · D** | |

## Facts side by side

| Fact | Letta | Sculptor |
| --- | --- | --- |
| Kind | Agent harness | Agent harness |
| Vendor | Letta | Imbue, Inc. |
| Hosted endpoint | no (local only) | no (local only) |
| Transports | stdio |  |
| Auth | OAuth or key | None |
| Pricing | Freemium | Free |
| x402 | no | no |
| Licence | Apache-2.0 | MIT |
| Read-only variant documented | no | no |
| llms.txt | yes | no |
| Last release | 2026-11-06 | 2026-11-06 |
| Terms last updated | no date given | no document linked |
| Privacy policy last updated | no date given | no document linked |
| Customer content may train models | not found in the text | not read yet |
| Terms restrict automated access | not found in the text | not read yet |
| Terms restrict benchmarking | not found in the text | not read yet |
| Terms or service can change without notice | not found in the text | not read yet |
| Arbitration or class-action waiver | yes | not read yet |
| Popularity | 3.8k stars, 86k npm/wk, 2.2k PyPI/wk | none |

## 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.

**Sculptor.** Imbue's open-source app for parallel coding agents in isolated workspaces, with telemetry off until you choose otherwise. It's an experimental research preview that warns of bugs and drastic changes, Mac and Linux only, with no changelog.

## Before you call either

### Letta

1. Start headless runs with an explicit permission mode such as `standard` or `strict`; the default auto-approves tools
2. Pass `--backend local` for work that must stay on the machine, since Letta Cloud is the default
3. Set LETTA_CODE_TELEM=0 in unattended runs if usage events must not be sent
4. Use `letta -p --output-format json` for scripted runs and parse the JSON, not the terminal output
5. Don't plan on the retired V1 REST server or `.af` AgentFile import; both are gone

### Sculptor

1. Download from the README's links, connect a repository and create a workspace before prompting
2. Review the diff before merging a workspace back to main

## Questions

### Which is better for AI agents, Letta or Sculptor?

Letta scores 59.7 (C) on agent readiness against Sculptor's 53.1 (D), and leads in 4 of 7 scored categories. Sculptor leads on security & auth.

### Are Letta and Sculptor open source?

Yes. Letta is open source (Apache-2.0). Sculptor is open source (MIT).


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/letta-vs-sculptor.json, and with the fewest tokens: https://www.anchorterminal.com/compare/letta-vs-sculptor.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "letta", "b": "sculptor"}`. From a terminal: `anchor compare letta sculptor`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/letta.json and https://www.anchorterminal.com/api/v1/tools/sculptor.json

## Other comparisons with Letta or Sculptor

- [Agent Zero vs Letta](https://www.anchorterminal.com/compare/agent-zero-vs-letta.md)
- [Agent Zero vs Sculptor](https://www.anchorterminal.com/compare/agent-zero-vs-sculptor.md)
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- [Amp vs Letta](https://www.anchorterminal.com/compare/amp-vs-letta.md)
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---

Query this catalogue directly over MCP: https://www.anchorterminal.com/mcp (Streamable HTTP, no key). How: https://www.anchorterminal.com/agents/#mcp