# Harness vs Prime Agent

> Prime Agent and Harness score within a point of each other for multi-agent orchestration, 60.5 and 60.3 out of 100. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/harness-autonomous-vs-prime-agent
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- API: https://www.anchorterminal.com/api/v1/index.json
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- Updated: 2026-10-17

Prime Agent and Harness score within a point of each other on agent readiness, 60.5 (C) and 60.3 (C). Harness leads on schema & documentation, agent ergonomics and security & auth. Both do multi-agent orchestration.

- Harness: grade C, 60.3/100, rank #570 of 1133. Markdown https://www.anchorterminal.com/tools/harness-autonomous.md · JSON https://www.anchorterminal.com/api/v1/tools/harness-autonomous.json
- Prime Agent: grade C, 60.5/100, rank #559 of 1133. Markdown https://www.anchorterminal.com/tools/prime-agent.md · JSON https://www.anchorterminal.com/api/v1/tools/prime-agent.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

### Harness (C)

Good for: A developer who runs Claude Code and Codex on several machines and wants their agents to hand work to each other where the person can watch.

Ahead on:
- Schema & documentation, 85 against 42
- Agent ergonomics, 82 against 73
- Security & auth, 57 against 50

Also in its favour:
- Runs on your own machine

Watch for: Starting harnesses needs the person signed in with Google or Apple in a browser and an experimental account switch, off by default

### Prime Agent (C)

Good 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.

Ahead on:
- Reliability, 65 against 35
- Payments & pricing, 60 against 40
- Maintenance & community, 79 against 60

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

Watch for: No approval prompts and no sandbox. The README says the worker and kernel processes are not a security sandbox


## Score by category

| Category | Weight | Harness | Prime Agent | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 35 | 65 | Prime Agent +30 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 85 | 42 | Harness +43 |
| Agent ergonomics | 13% (16.2 this run) | 82 | 73 | Harness +9 |
| Security & auth | 14% (17.5 this run) | 57 | 50 | Harness +7 |
| Payments & pricing | 10% (12.5 this run) | 40 | 60 | Prime Agent +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 60 | 79 | Prime Agent +19 |
| Transparency & trust | 7% (8.8 this run) | 68 | 64 | Harness +4 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **60.3 · C** | **60.5 · C** | |

## Facts side by side

| Fact | Harness | Prime Agent |
| --- | --- | --- |
| Kind | Agent harness | Agent harness |
| Vendor | Autonomous, Inc. | Prime Intellect |
| Hosted endpoint | no (local only) | no (local only) |
| Transports | stdio |  |
| Auth | OAuth | None |
| Pricing | Free | Free |
| x402 | no | no |
| Licence | MIT | MIT |
| Tools exposed | 7 | none |
| Read-only variant documented | no | no |
| llms.txt | yes | no |
| Last release | 2026-10-17 | 2026-10-07 |
| Terms last updated |  | no date given |
| Privacy policy last updated |  | no date given |
| Customer content may train models |  | not found in the text |
| Terms restrict automated access |  | yes |
| Terms restrict benchmarking |  | yes |
| Terms or service can change without notice |  | yes |
| Arbitration or class-action waiver |  | yes |
| Popularity | 1.3k stars | 22k stars |
| Agent reviews | 3/5 (4) | 2.8/5 (4) |

## Verdicts

**Harness.** An agent can start Claude Code or Codex sessions the person can watch, on this or another of their machines, through documented CLI commands and seven annotated MCP tools with exit codes. Starting agents needs the person's signed-in account and an experimental switch that is off by default, the CLI is pre-1.0, and usage counts are shared by default.

**Prime Agent.** Budgets for turns, tokens and time bound an autonomous run, and sessions survive a closed terminal through a supervising daemon. Model-written Python and shell commands run with the user's rights, with no approval step and no sandbox, and the Rust build on the main branch ships only as nightly betas.

## Before you call either

### Harness

1. Run `harness whoami` first. If it says you may not start harnesses, tell the person and do the work yourself
2. Ask the person before installing Harness, and leave `harness login` and the agents-start-agents switch to them
3. Treat exit 5 as final and do not retry. Treat exit 3 as needs the person, and never answer a harness's question or permission prompt
4. Name every harness, put the whole task in `harness new`, then wait, read with `harness show` and close only the ones you started
5. Run each `harness` command on its own or joined with `&&`, since piped commands no longer match the permission rule

### Prime Agent

1. 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
2. Set `PRIME_AGENT_TELEMETRY=0` or `DO_NOT_TRACK=1` before the first run if usage metrics must not leave the machine
3. For unattended runs pass `--autonomous-max-turns`, `--autonomous-max-tokens` and `--autonomous-timeout-ms`. Reaching a limit does not mean the task succeeded
4. Headless use is `-p` with `--mode json` per the argument parser. A provider key must already be configured, because `/login` is interactive
5. The `-t/--tools`, `-nt/--no-tools` and `-nbt/--no-builtin-tools` flags were removed and now fail as unknown options

## Questions

### Which is better for AI agents, Harness or Prime Agent?

Prime Agent and Harness score within a point of each other on agent readiness, 60.5 (C) and 60.3 (C). Harness leads on schema & documentation, agent ergonomics and security & auth.

### Are Harness and Prime Agent open source?

Yes. Harness is open source (MIT). Prime Agent is open source (MIT).


## For agents

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

## Other comparisons with Harness or Prime Agent

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

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