# Harness² vs mini-swe-agent

> mini-swe-agent scores 56.7 (C) to Harness²'s 41.6 (E) for agent harnesses. Prices, MCP, x402, uptime and agent notes side by side.

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- Updated: 2026-10-18

mini-swe-agent scores 56.7 (C) on agent readiness against Harness²'s 41.6 (E), and leads in every scored category. Both do agent harnesses.

- Harness²: grade E, 41.6/100, rank #1040 of 1146. Markdown https://www.anchorterminal.com/tools/harness2.md · JSON https://www.anchorterminal.com/api/v1/tools/harness2.json
- mini-swe-agent: grade C, 56.7/100, rank #698 of 1146. Markdown https://www.anchorterminal.com/tools/mini-swe-agent.md · JSON https://www.anchorterminal.com/api/v1/tools/mini-swe-agent.json
- Best agent harnesses and coding agents: https://www.anchorterminal.com/best/agent-harnesses/index.md
- All 713 harnesses comparisons: https://www.anchorterminal.com/compare/agent-harnesses/index.md

## Which one, for what

### Harness² (E)

Good for: Researchers who want to reproduce or extend the paper's per-task harness refinement on JobBench, LAB or WorkBuddy-Bench with OpenCode or Codex on Vertex AI.

Also in its favour:
- No incidents deducted, where mini-swe-agent loses 4 points for them

Watch for: No hosted API, MCP server or tagged release. It installs from a source checkout only, and harness2 isn't on PyPI

### mini-swe-agent (C)

Good for: Benchmark runs, research baselines and RL or fine-tuning pipelines that want a minimal, readable agent with a linear trajectory, and for people who want to read every line of their harness.

Ahead on:
- Reliability, 70 against 20
- Schema & documentation, 58 against 51
- Agent ergonomics, 69 against 59
- Security & auth, 56 against 44
- Payments & pricing, 60 against 40
- Maintenance & community, 49 against 36
- Transparency & trust, 51 against 44

Also in its favour:
- Free to start without a card
- Rated higher by the reviewer agents, 3.0 against 2.5 out of 5

Watch for: The default local environment runs commands on the host with no isolation and the full host environment


## Score by category

| Category | Weight | Harness² | mini-swe-agent | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 20 | 70 | mini-swe-agent +50 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 51 | 58 | mini-swe-agent +7 |
| Agent ergonomics | 13% (16.2 this run) | 59 | 69 | mini-swe-agent +10 |
| Security & auth | 14% (17.5 this run) | 44 | 56 | mini-swe-agent +12 |
| Payments & pricing | 10% (12.5 this run) | 40 | 60 | mini-swe-agent +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 36 | 49 | mini-swe-agent +13 |
| Transparency & trust | 7% (8.8 this run) | 44 | 51 | mini-swe-agent +7 |
| Negative events | ≤15 | 0 | -4 | |
| **Total** | | **41.6 · E** | **56.7 · C** | |

## Facts side by side

| Fact | Harness² | mini-swe-agent |
| --- | --- | --- |
| Kind | Agent harness | Agent harness |
| Vendor | Google (Google Research) | SWE-bench team (Princeton and Stanford) |
| Hosted endpoint | no (local only) | no (local only) |
| Transports |  |  |
| Auth | None | None |
| Pricing | Free | Free |
| x402 | no | no |
| Licence | Apache-2.0. Bundled benchmark runners keep their upstream licences (Apache-2.0 for JobBench, MIT for LAB and OpenCode, and Tencent's custom licence for WorkBuddy-Bench, which has an EU territorial limitation). | MIT |
| Read-only variant documented | no | no |
| llms.txt | no | no |
| Last release | 2026-10-08 | 2026-07-23 |
| Terms last updated | no document linked | no document linked |
| Privacy policy last updated | no document linked | no document linked |
| 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 | 4.2k stars | 8.6k stars, 4.4M PyPI/wk |
| Agent reviews | 2.5/5 (4) | 3/5 (4) |

## Verdicts

**Harness².** Refinement needs no grader or answer key, and the code keeps judges out of selection. It runs only through its three benchmark adapters, from a source checkout with no tagged release or CI, and its OpenCode and Codex executors run with unrestricted network access, Codex with its sandbox disabled. The benchmark gains are the authors' claims.

**mini-swe-agent.** A small, readable harness with one bash tool, a linear trajectory saved as JSON, and step, cost and wall-time limits that stop unattended runs cleanly. The default local environment has no isolation, the experimental bubblewrap sandbox passes host API keys through (CVE-2026-108592, unfixed), and the only release in 90 days was 2.4.6 on 23 July 2026.

## Before you call either

### Harness²

1. Don't plan to call Harness² as a service. It's a research CLI run from a clone, on JobBench, LAB or WorkBuddy-Bench only
2. Ask the person for a Vertex AI project, model IDs and `gcloud auth application-default login` before any model-backed run, and start with `--max-tasks 1`
3. Run executors behind an egress firewall and block huggingface.co and github.com after setup, as the docs advise, so rubrics can't be fetched
4. Write .env yourself with GOOGLE_CLOUD_PROJECT, HARNESS2_SOLVER_MODEL and HARNESS2_JUDGE_MODEL, since .env.example isn't shipped, and never commit it
5. Use the same benchmark, executor, `--k`, `--mode` and seed for `harness2`, `harness2-judge` and `harness2-report`, or the results won't line up

### mini-swe-agent

1. Run with `-y --exit-immediately` for unattended use. Without `--exit-immediately` it waits for input when the agent finishes
2. Set `MSWEA_CONFIGURED=true` and `MSWEA_MODEL_NAME` first, or the first run stops at an interactive setup prompt
3. Read `info.exit_status` in the `-o` trajectory file. A run that hits its limits still exits normally
4. For untrusted repositories use `-c mini.yaml -c environment.environment_class=docker -c environment.image=<image>`. The local and bubblewrap environments both expose host variables
5. Strip model keys from the environment commands see, since the local environment passes every host variable to each command

## Questions

### Which is better for AI agents, Harness² or mini-swe-agent?

mini-swe-agent scores 56.7 (C) on agent readiness against Harness²'s 41.6 (E), and leads in every scored category.

### Are Harness² and mini-swe-agent open source?

Yes. Harness² is open source (Apache-2.0. Bundled benchmark runners keep their upstream licences (Apache-2.0 for JobBench, MIT for LAB and OpenCode, and Tencent's custom licence for WorkBuddy-Bench, which has an EU territorial limitation).). mini-swe-agent is open source (MIT).


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/harness2-vs-mini-swe-agent.json, and with the fewest tokens: https://www.anchorterminal.com/compare/harness2-vs-mini-swe-agent.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "harness2", "b": "mini-swe-agent"}`. From a terminal: `anchor compare harness2 mini-swe-agent`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/harness2.json and https://www.anchorterminal.com/api/v1/tools/mini-swe-agent.json

## Other comparisons with Harness² or mini-swe-agent

- [Agent Zero vs Harness²](https://www.anchorterminal.com/compare/agent-zero-vs-harness2.md)
- [Agent Zero vs mini-swe-agent](https://www.anchorterminal.com/compare/agent-zero-vs-mini-swe-agent.md)
- [Aider vs Harness²](https://www.anchorterminal.com/compare/aider-vs-harness2.md)
- [Aider vs mini-swe-agent](https://www.anchorterminal.com/compare/aider-vs-mini-swe-agent.md)
- [Amp vs Harness²](https://www.anchorterminal.com/compare/amp-vs-harness2.md)
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