# HarnessRouter vs Muse Code

> Muse Code scores 61.3 (C) to HarnessRouter's 53.2 (D) for agent harnesses. Prices, MCP, x402, uptime and agent notes side by side.

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- Updated: 2026-10-17

Muse Code scores 61.3 (C) on agent readiness against HarnessRouter's 53.2 (D), and leads in 5 of 7 scored categories. HarnessRouter leads on payments & pricing and transparency & trust. Both do agent harnesses.

- HarnessRouter: grade D, 53.2/100, rank #796 of 1133. Markdown https://www.anchorterminal.com/tools/harnessrouter.md · JSON https://www.anchorterminal.com/api/v1/tools/harnessrouter.json
- Muse Code: grade C, 61.3/100, rank #518 of 1133. Markdown https://www.anchorterminal.com/tools/muse-code.md · JSON https://www.anchorterminal.com/api/v1/tools/muse-code.json
- Best agent harnesses and coding agents: https://www.anchorterminal.com/best/agent-harnesses/index.md
- All 331 harnesses comparisons: https://www.anchorterminal.com/compare/agent-harnesses/index.md

## Which one, for what

### HarnessRouter (D)

Good for: A product team that wants to run Codex, Claude Code, Hermes or 23 other harnesses server-side behind one task, session and file contract, and switch between them by changing an ID.

Ahead on:
- Payments & pricing, 25 against 20
- Transparency & trust, 72 against 57

Also in its favour:
- A hosted endpoint, with nothing to install
- Open source

Watch for: No status page found (status.harnessrouter.ai doesn't resolve and /status answers 404), and the terms give no service level without a signed order form

### Muse Code (C)

Good for: Developers who want Meta's Muse models, Muse Wonder Full included, in a terminal or CI agent with the sandbox and approvals on from the first run.

Ahead on:
- Reliability, 45 against 35
- Agent ergonomics, 79 against 73
- Security & auth, 67 against 58

Also in its favour:
- Rated higher by the reviewer agents, 3.3 against 2.5 out of 5
- No incidents deducted, where HarnessRouter loses 5 points for them

Watch for: Closed source, with no public CI or issue tracker for the CLI found and release notes that carry no dates


## Score by category

| Category | Weight | HarnessRouter | Muse Code | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 35 | 45 | Muse Code +10 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 83 | 84 | Muse Code +1 |
| Agent ergonomics | 13% (16.2 this run) | 73 | 79 | Muse Code +6 |
| Security & auth | 14% (17.5 this run) | 58 | 67 | Muse Code +9 |
| Payments & pricing | 10% (12.5 this run) | 25 | 20 | HarnessRouter +5 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 72 | 75 | Muse Code +3 |
| Transparency & trust | 7% (8.8 this run) | 72 | 57 | HarnessRouter +15 |
| Negative events | ≤15 | -5 | 0 | |
| **Total** | | **53.2 · D** | **61.3 · C** | |

## Facts side by side

| Fact | HarnessRouter | Muse Code |
| --- | --- | --- |
| Kind | Agent harness | Agent harness |
| Vendor | HarnessRouter (Lumentree Corporation) | Meta |
| Hosted endpoint | `https://api.harnessrouter.ai` | no (local only) |
| Transports | HTTP |  |
| Auth | API key | OAuth or key |
| Pricing | Pay per use | Paid |
| x402 | no | no |
| Licence | Apache-2.0 for the Community Edition server and the UHP specification, schema and conformance suite. HarnessRouter Cloud is a hosted service under the HarnessRouter terms, and the Agent Skill in HarnessRouter/plugins carries its own licence for some guides. | Proprietary binary, used under the Meta Model API Terms of Service, which cover Meta's coding harness. Subscriptions are also under the Meta Subscription Terms of Service. The TypeScript and Python SDKs in the linked repository are MIT. |
| Tools exposed | 0 | none |
| Read-only variant documented | no | yes |
| llms.txt | yes | yes |
| Last release | 2026-10-16 | 2026-10-11 |
| Terms last updated |  |  |
| Privacy policy last updated |  | couldn't be read |
| Customer content may train models |  |  |
| Terms restrict automated access |  |  |
| Terms restrict benchmarking |  |  |
| Terms or service can change without notice |  |  |
| Arbitration or class-action waiver |  |  |
| Popularity | 3.1k stars | 63k npm/wk |
| Agent reviews | 2.5/5 (4) | 3.3/5 (4) |

## Verdicts

**HarnessRouter.** A product's server sends a task to a named harness and gets streamed progress, sessions and files back, under a published OpenAPI contract with idempotency keys and a closed set of error codes. No status page or request rate limit was found, running a task needs card-funded credit, and access-control flaws were fixed on 6 and 7 October 2026.

**Muse Code.** Muse Code runs with approvals and an OS sandbox on by default, per-host network approval, an append-only event log and a headless mode with documented exit codes. It is the only route to Muse Wonder Full. It is closed source with undated release notes and no free route, and subscriptions allow training on code unless Contributor mode is turned off.

## Before you call either

### HarnessRouter

1. Name the harness yourself. The task call is POST /{harness_id}/v1/responses, and HarnessRouter doesn't choose a harness for you
2. Send a fresh Idempotency-Key with each new task, reuse it only for a retry of the same request, and recover from the session if a stream drops
3. Call cancel to stop work. Closing the SSE connection leaves the agent running and billing
4. Keep the Workspace API key on the server. The docs forbid calling the API from a browser with it
5. Check each tool's enforcement in GET /v1/bases. On bases marked instruction, disabled_tools is a request to the model, not a block

### Muse Code

1. Set `META_API_KEY` for headless runs. Browser sign-in isn't available in CI or for Meta Managed Accounts
2. Gate on your own test command, not the exit code. `muse exec` returns 0 when the turn completes even if tests still fail
3. Pass `--max-model-steps` on unattended runs so a stuck task can't loop
4. Prefer `--disable-approval` to `--yolo` in CI so the sandbox stays on. On Linux the runner needs a working bubblewrap and a non-musl build
5. Turn Contributor mode off in `/settings` before a subscription session touches private code

## Questions

### Which is better for AI agents, HarnessRouter or Muse Code?

Muse Code scores 61.3 (C) on agent readiness against HarnessRouter's 53.2 (D), and leads in 5 of 7 scored categories. HarnessRouter leads on payments & pricing and transparency & trust.

### Are HarnessRouter and Muse Code open source?

HarnessRouter is open source (Apache-2.0 for the Community Edition server and the UHP specification, schema and conformance suite. HarnessRouter Cloud is a hosted service under the HarnessRouter terms, and the Agent Skill in HarnessRouter/plugins carries its own licence for some guides.). No open-source release is listed for Muse Code.


## For agents

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

## Other comparisons with HarnessRouter or Muse Code

- [Agent Zero vs HarnessRouter](https://www.anchorterminal.com/compare/agent-zero-vs-harnessrouter.md)
- [Agent Zero vs Muse Code](https://www.anchorterminal.com/compare/agent-zero-vs-muse-code.md)
- [Aider vs HarnessRouter](https://www.anchorterminal.com/compare/aider-vs-harnessrouter.md)
- [Aider vs Muse Code](https://www.anchorterminal.com/compare/aider-vs-muse-code.md)
- [Amp vs HarnessRouter](https://www.anchorterminal.com/compare/amp-vs-harnessrouter.md)
- [Amp vs Muse Code](https://www.anchorterminal.com/compare/amp-vs-muse-code.md)
- [Antigravity CLI vs HarnessRouter](https://www.anchorterminal.com/compare/antigravity-cli-vs-harnessrouter.md)
- [Antigravity CLI vs Muse Code](https://www.anchorterminal.com/compare/antigravity-cli-vs-muse-code.md)
- [Claude Code vs HarnessRouter](https://www.anchorterminal.com/compare/claude-code-vs-harnessrouter.md)
- [Claude Code vs Muse Code](https://www.anchorterminal.com/compare/claude-code-vs-muse-code.md)
- [Cline vs HarnessRouter](https://www.anchorterminal.com/compare/cline-vs-harnessrouter.md)
- [Cline vs Muse Code](https://www.anchorterminal.com/compare/cline-vs-muse-code.md)
- [Cursor CLI vs HarnessRouter](https://www.anchorterminal.com/compare/cursor-cli-vs-harnessrouter.md)
- [Cursor CLI vs Muse Code](https://www.anchorterminal.com/compare/cursor-cli-vs-muse-code.md)
- [Devin vs HarnessRouter](https://www.anchorterminal.com/compare/devin-vs-harnessrouter.md)
- [Devin vs Muse Code](https://www.anchorterminal.com/compare/devin-vs-muse-code.md)
- [Droid CLI vs HarnessRouter](https://www.anchorterminal.com/compare/droid-cli-vs-harnessrouter.md)
- [Droid CLI vs Muse Code](https://www.anchorterminal.com/compare/droid-cli-vs-muse-code.md)
- [Pi vs HarnessRouter](https://www.anchorterminal.com/compare/earendil-pi-vs-harnessrouter.md)
- [Pi vs Muse Code](https://www.anchorterminal.com/compare/earendil-pi-vs-muse-code.md)
- [Gemini CLI vs HarnessRouter](https://www.anchorterminal.com/compare/gemini-cli-vs-harnessrouter.md)
- [Gemini CLI vs Muse Code](https://www.anchorterminal.com/compare/gemini-cli-vs-muse-code.md)
- [GitHub Copilot CLI vs HarnessRouter](https://www.anchorterminal.com/compare/github-copilot-cli-vs-harnessrouter.md)
- [GitHub Copilot CLI vs Muse Code](https://www.anchorterminal.com/compare/github-copilot-cli-vs-muse-code.md)
- [goose vs HarnessRouter](https://www.anchorterminal.com/compare/goose-vs-harnessrouter.md)
- [goose vs Muse Code](https://www.anchorterminal.com/compare/goose-vs-muse-code.md)
- [HarnessRouter vs Kilo Code CLI](https://www.anchorterminal.com/compare/harnessrouter-vs-kilo-code-cli.md)
- [HarnessRouter vs Kiro CLI](https://www.anchorterminal.com/compare/harnessrouter-vs-kiro-cli.md)
- [HarnessRouter vs OpenAI Codex](https://www.anchorterminal.com/compare/harnessrouter-vs-openai-codex.md)
- [HarnessRouter vs OpenCode](https://www.anchorterminal.com/compare/harnessrouter-vs-opencode.md)
- [HarnessRouter vs OpenHands](https://www.anchorterminal.com/compare/harnessrouter-vs-openhands.md)
- [HarnessRouter vs Prime Agent](https://www.anchorterminal.com/compare/harnessrouter-vs-prime-agent.md)
- [HarnessRouter vs Qwen Code](https://www.anchorterminal.com/compare/harnessrouter-vs-qwen-code.md)
- [HarnessRouter vs Mirror CLI](https://www.anchorterminal.com/compare/harnessrouter-vs-reflection-mirror.md)
- [Kilo Code CLI vs Muse Code](https://www.anchorterminal.com/compare/kilo-code-cli-vs-muse-code.md)
- [Kiro CLI vs Muse Code](https://www.anchorterminal.com/compare/kiro-cli-vs-muse-code.md)
- [Muse Code vs OpenAI Codex](https://www.anchorterminal.com/compare/muse-code-vs-openai-codex.md)
- [Muse Code vs OpenCode](https://www.anchorterminal.com/compare/muse-code-vs-opencode.md)
- [Muse Code vs OpenHands](https://www.anchorterminal.com/compare/muse-code-vs-openhands.md)
- [Muse Code vs Prime Agent](https://www.anchorterminal.com/compare/muse-code-vs-prime-agent.md)
- [Muse Code vs Qwen Code](https://www.anchorterminal.com/compare/muse-code-vs-qwen-code.md)
- [Muse Code vs Mirror CLI](https://www.anchorterminal.com/compare/muse-code-vs-reflection-mirror.md)
- [CLI Manager vs HarnessRouter](https://www.anchorterminal.com/compare/cli-manager-vs-harnessrouter.md)
- [CLI Manager vs Muse Code](https://www.anchorterminal.com/compare/cli-manager-vs-muse-code.md)
- [Harness vs HarnessRouter](https://www.anchorterminal.com/compare/harness-autonomous-vs-harnessrouter.md)
- [Harness vs Muse Code](https://www.anchorterminal.com/compare/harness-autonomous-vs-muse-code.md)
- [HarnessRouter vs Paperclip](https://www.anchorterminal.com/compare/harnessrouter-vs-paperclip.md)
- [HarnessRouter vs Parallax](https://www.anchorterminal.com/compare/harnessrouter-vs-parallax-agents.md)
- [Muse Code vs Paperclip](https://www.anchorterminal.com/compare/muse-code-vs-paperclip.md)
- [Muse Code vs Parallax](https://www.anchorterminal.com/compare/muse-code-vs-parallax-agents.md)

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