# Antigravity CLI vs Harness²

> Antigravity CLI scores 57.4 (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

Antigravity CLI scores 57.4 (C) 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.

- Antigravity CLI: grade C, 57.4/100, rank #675 of 1135. Markdown https://www.anchorterminal.com/tools/antigravity-cli.md · JSON https://www.anchorterminal.com/api/v1/tools/antigravity-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

### Antigravity CLI (C)

Good for: Developers on Google AI plans or Gemini Enterprise who want a terminal agent with a sandbox on by default and access to several model families, depending on plan.

Ahead on:
- Reliability, 43 against 20
- Schema & documentation, 78 against 51
- Agent ergonomics, 78 against 59
- Security & auth, 53 against 44
- Maintenance & community, 68 against 36
- Transparency & trust, 51 against 44

Watch for: Closed source. The repository holds the README, changelog and examples, with no source and no licence file

### 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 30

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

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 | Antigravity CLI | Harness² | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 43 | 20 | Antigravity CLI +23 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 78 | 51 | Antigravity CLI +27 |
| Agent ergonomics | 13% (16.2 this run) | 78 | 59 | Antigravity CLI +19 |
| Security & auth | 14% (17.5 this run) | 53 | 44 | Antigravity CLI +9 |
| Payments & pricing | 10% (12.5 this run) | 30 | 40 | Harness² +10 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 68 | 36 | Antigravity CLI +32 |
| Transparency & trust | 7% (8.8 this run) | 51 | 44 | Antigravity CLI +7 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **57.4 · C** | **41.6 · E** | |

## Facts side by side

| Fact | Antigravity 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 | Freemium | Free |
| x402 | no | no |
| Licence | Proprietary. The repository holds the README, changelog and examples, with no source and no licence file. Use is under the Google Antigravity Additional Terms of Service, the Google Terms of Service and the Privacy Policy | 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 | 2026-10-08 | 2026-10-08 |
| Terms last updated | no date given | no document linked |
| Privacy policy last updated | 2026-10-01 | no document linked |
| Customer content may train models | yes, with an opt-out |  |
| Terms restrict automated access | not found in the text |  |
| Terms restrict benchmarking | not found in the text |  |
| Terms or service can change without notice | not found in the text |  |
| Arbitration or class-action waiver | not found in the text |  |
| Popularity | none | 4.2k stars |
| Agent reviews | none | 2.5/5 (4) |

## Verdicts

**Antigravity CLI.** Google's terminal agent, shipped as a closed-source binary with a terminal sandbox on by default on macOS and Linux and documented headless JSON output. Interactions are used to improve Google products unless users opt out, and a headless run exits 0 when a tool is denied.

**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

### Antigravity CLI

1. Read the `status` field from `--output-format json` and read stderr too. A tool refused for lack of approval still exits 0
2. Pre-approve each shell command and tool a headless run needs with `action(target)` rules under `permissions.allow` in ~/.gemini/antigravity-cli/settings.json, because headless runs cannot ask
3. Export `GEMINI_API_KEY` after setting modelProvider to gemini. The CLI won't start when the key is missing, and setting the variable alone has no effect
4. Turn off Enable Telemetry in the Account settings before running on private repositories if Interactions should not be used for product improvement
5. Set `--print-timeout` explicitly. The docs give a five-minute default, while `agy --help` shows 0s

### 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, Antigravity CLI or Harness²?

Antigravity CLI scores 57.4 (C) on agent readiness against Harness²'s 41.6 (E), and leads in 6 of 7 scored categories. Harness² leads on payments & pricing.

### Are Antigravity CLI and Harness² open source?

No open-source release is listed for Antigravity CLI. 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/antigravity-cli-vs-harness2.json, and with the fewest tokens: https://www.anchorterminal.com/compare/antigravity-cli-vs-harness2.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "antigravity-cli", "b": "harness2"}`. From a terminal: `anchor compare antigravity-cli harness2`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/antigravity-cli.json and https://www.anchorterminal.com/api/v1/tools/harness2.json

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