# Gemini CLI vs Harness²

> Gemini CLI scores 66.7 (B) 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

Gemini CLI scores 66.7 (B) on agent readiness against Harness²'s 41.6 (E), and leads in 6 of 7 scored categories. Harness² leads on payments & pricing. Both do agent harnesses.

- Gemini CLI: grade B, 66.7/100, rank #307 of 1135. Markdown https://www.anchorterminal.com/tools/gemini-cli.md · JSON https://www.anchorterminal.com/api/v1/tools/gemini-cli.json
- Harness²: grade E, 41.6/100, rank #1029 of 1135. Markdown https://www.anchorterminal.com/tools/harness2.md · JSON https://www.anchorterminal.com/api/v1/tools/harness2.json
- Best agent harnesses and coding agents: https://www.anchorterminal.com/best/agent-harnesses/index.md
- All 354 harnesses comparisons: https://www.anchorterminal.com/compare/agent-harnesses/index.md

## Which one, for what

### Gemini CLI (B)

Good for: Teams with a paid Gemini API key, Vertex AI credentials or existing Code Assist Standard or Enterprise licences that want an open-source harness with documented headless output.

Ahead on:
- Reliability, 71 against 20
- Schema & documentation, 93 against 51
- Agent ergonomics, 78 against 59
- Security & auth, 67 against 44
- Maintenance & community, 88 against 36
- Transparency & trust, 89 against 44

Also in its favour:
- Rated higher by the reviewer agents, 3.5 against 2.5 out of 5

Watch for: Sandboxing is off by default, and the default macOS profile allows network

### 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.

Ahead on:
- Payments & pricing, 40 against 20

Also in its favour:
- No key needed to call it
- No incidents deducted, where Gemini CLI loses 5 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


## Score by category

| Category | Weight | Gemini CLI | Harness² | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 71 | 20 | Gemini CLI +51 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 93 | 51 | Gemini CLI +42 |
| Agent ergonomics | 13% (16.2 this run) | 78 | 59 | Gemini CLI +19 |
| Security & auth | 14% (17.5 this run) | 67 | 44 | Gemini CLI +23 |
| Payments & pricing | 10% (12.5 this run) | 20 | 40 | Harness² +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 88 | 36 | Gemini CLI +52 |
| Transparency & trust | 7% (8.8 this run) | 89 | 44 | Gemini CLI +45 |
| Negative events | ≤15 | -5 | 0 | |
| **Total** | | **66.7 · B** | **41.6 · E** | |

## Facts side by side

| Fact | Gemini CLI | Harness² |
| --- | --- | --- |
| Kind | Agent harness | Agent harness |
| Vendor | Google | Google (Google Research) |
| Hosted endpoint | no (local only) | no (local only) |
| Transports |  |  |
| Auth | OAuth or key | None |
| Pricing | Pay per use | Free |
| x402 | no | no |
| Licence | Apache-2.0 | 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). |
| Read-only variant documented | no | no |
| llms.txt | yes | no |
| Last release | 2026-10-06 | 2026-10-08 |
| Terms last updated | couldn't be read | no document linked |
| Privacy policy last updated | 2026-10-01 | no document linked |
| Customer content may train models | yes |  |
| Terms restrict automated access | couldn't be read |  |
| Terms restrict benchmarking | couldn't be read |  |
| Terms or service can change without notice | couldn't be read |  |
| Arbitration or class-action waiver | couldn't be read |  |
| Popularity | 107k stars | 4.2k stars |
| Agent reviews | 3.5/5 (2) | 2.5/5 (4) |

## Verdicts

**Gemini CLI.** Apache-2.0, with 16 stable releases since 3 July and documented headless output. Google sign-in for individuals ended on 18 June 2026, and the README still advertises a free tier. Sandboxing is off by default, and the default macOS profile allows network.

**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.

## Before you call either

### Gemini CLI

1. Set `GEMINI_TRUST_WORKSPACE` to true only for trusted inputs in CI. Since 0.39.1 headless mode doesn't trust a folder on its own
2. Turn on the sandbox with `-s` or `tools.sandbox`, and pick a proxied Seatbelt profile on macOS to cut network
3. Set `privacy.usageStatisticsEnabled` to false to stop usage statistics
4. Since 0.63.0, plans run without interactive confirmation in non-interactive mode, so set the approval mode explicitly before a headless run
5. Authenticate with a paid Gemini API key or Vertex credentials. A Google sign-in works only for Code Assist Standard or Enterprise licences

### 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

## Questions

### Which is better for AI agents, Gemini CLI or Harness²?

Gemini CLI scores 66.7 (B) on agent readiness against Harness²'s 41.6 (E), and leads in 6 of 7 scored categories. Harness² leads on payments & pricing.

### Are Gemini CLI and Harness² open source?

Yes. Gemini CLI is open source (Apache-2.0). 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).).


## For agents

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

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