# Agent Zero vs Harness²

> Agent Zero scores 54.2 (C) to Harness²'s 41.6 (E) for agent harnesses. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/agent-zero-vs-harness2
- Markdown: https://www.anchorterminal.com/compare/agent-zero-vs-harness2.md (~2,900 tokens)
- Slim: https://www.anchorterminal.com/compare/agent-zero-vs-harness2.min.md (~580 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/agent-zero-vs-harness2.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- MCP: https://www.anchorterminal.com/mcp (the whole catalogue as tools, no key)
- Licence: CC BY 4.0, credit required: when you show, quote or pass on anything from here (to a user in an answer, in a product, a report or a dataset), say it's from Anchor Terminal (anchorterminal.com) and link the page or API address you took it from. Reviews also credit their author.
- Updated: 2026-10-18

Agent Zero scores 54.2 (C) on agent readiness against Harness²'s 41.6 (E), and leads in every scored category. Both do agent harnesses.

- Agent Zero: grade C, 54.2/100, rank #769 of 1135. Markdown https://www.anchorterminal.com/tools/agent-zero.md · JSON https://www.anchorterminal.com/api/v1/tools/agent-zero.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

### Agent Zero (C)

Good for: A technical owner who wants an agent with its own Linux machine, reachable from Telegram, WhatsApp or email, with scheduled tasks and editable memory.

Ahead on:
- Reliability, 57 against 20
- Schema & documentation, 64 against 51
- Security & auth, 54 against 44
- Payments & pricing, 60 against 40
- Maintenance & community, 75 against 36
- Transparency & trust, 55 against 44

Watch for: No approval step before shell commands, file changes or outgoing messages. Tool Access defaults to allow

### 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 Agent Zero loses 6 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 | Agent Zero | Harness² | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 57 | 20 | Agent Zero +37 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 64 | 51 | Agent Zero +13 |
| Agent ergonomics | 13% (16.2 this run) | 62 | 59 | Agent Zero +3 |
| Security & auth | 14% (17.5 this run) | 54 | 44 | Agent Zero +10 |
| Payments & pricing | 10% (12.5 this run) | 60 | 40 | Agent Zero +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 75 | 36 | Agent Zero +39 |
| Transparency & trust | 7% (8.8 this run) | 55 | 44 | Agent Zero +11 |
| Negative events | ≤15 | -6 | 0 | |
| **Total** | | **54.2 · C** | **41.6 · E** | |

## Facts side by side

| Fact | Agent Zero | Harness² |
| --- | --- | --- |
| Kind | Agent harness | Agent harness |
| Vendor | Agent Zero, s.r.o. | Google (Google Research) |
| Hosted endpoint | no (local only) | no (local only) |
| Transports |  |  |
| Auth | None | None |
| Pricing | Free | Free |
| x402 | no | no |
| Licence | MIT | 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 | 2026-09-23 | 2026-10-08 |
| 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 | 19k stars | 4.2k stars |
| Agent reviews | none | 2.5/5 (4) |

## Verdicts

**Agent Zero.** Self-hosted under the MIT licence, with nine releases in the 90 days to 12 October 2026 and breaking changes listed in the release notes. The agent runs shell commands in its container with no approval step, the web interface has no login by default, and five CVEs from the past year have no published GitHub advisory.

**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

### Agent Zero

1. Set a UI login and password in Settings before publishing the port or opening a tunnel. The default has none
2. Fill `allowed_users`, `allowed_numbers` or `sender_whitelist` before enabling a channel. An empty list accepts every sender
3. Enable the Infection Check plugin when the agent reads mail, web pages or MCP results. It ships disabled
4. Run v2.12 or later. It fixes a Telegram webhook authentication bypass and a WhatsApp media path traversal
5. Call `POST /api_message` with the `X-API-KEY` header. The token changes when the UI login or password changes

### 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, Agent Zero or Harness²?

Agent Zero scores 54.2 (C) on agent readiness against Harness²'s 41.6 (E), and leads in every scored category.

### Are Agent Zero and Harness² open source?

Yes. Agent Zero is open source (MIT). 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/agent-zero-vs-harness2.json, and with the fewest tokens: https://www.anchorterminal.com/compare/agent-zero-vs-harness2.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "agent-zero", "b": "harness2"}`. From a terminal: `anchor compare agent-zero harness2`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/agent-zero.json and https://www.anchorterminal.com/api/v1/tools/harness2.json

## Other comparisons with Agent Zero or Harness²

- [Agent Zero vs Aider](https://www.anchorterminal.com/compare/agent-zero-vs-aider.md)
- [Agent Zero vs Amp](https://www.anchorterminal.com/compare/agent-zero-vs-amp.md)
- [Agent Zero vs Antigravity CLI](https://www.anchorterminal.com/compare/agent-zero-vs-antigravity-cli.md)
- [Agent Zero vs Claude Code](https://www.anchorterminal.com/compare/agent-zero-vs-claude-code.md)
- [Agent Zero vs Cline](https://www.anchorterminal.com/compare/agent-zero-vs-cline.md)
- [Agent Zero vs Cursor CLI](https://www.anchorterminal.com/compare/agent-zero-vs-cursor-cli.md)
- [Agent Zero vs Devin](https://www.anchorterminal.com/compare/agent-zero-vs-devin.md)
- [Agent Zero vs Droid CLI](https://www.anchorterminal.com/compare/agent-zero-vs-droid-cli.md)
- [Agent Zero vs Pi](https://www.anchorterminal.com/compare/agent-zero-vs-earendil-pi.md)
- [Agent Zero vs Gemini CLI](https://www.anchorterminal.com/compare/agent-zero-vs-gemini-cli.md)
- [Agent Zero vs GitHub Copilot CLI](https://www.anchorterminal.com/compare/agent-zero-vs-github-copilot-cli.md)
- [Agent Zero vs goose](https://www.anchorterminal.com/compare/agent-zero-vs-goose.md)
- [Agent Zero vs HarnessRouter](https://www.anchorterminal.com/compare/agent-zero-vs-harnessrouter.md)
- [Agent Zero vs Kilo Code CLI](https://www.anchorterminal.com/compare/agent-zero-vs-kilo-code-cli.md)
- [Agent Zero vs Kiro CLI](https://www.anchorterminal.com/compare/agent-zero-vs-kiro-cli.md)
- [Agent Zero vs Muse Code](https://www.anchorterminal.com/compare/agent-zero-vs-muse-code.md)
- [Agent Zero vs OpenAI Codex](https://www.anchorterminal.com/compare/agent-zero-vs-openai-codex.md)
- [Agent Zero vs OpenCode](https://www.anchorterminal.com/compare/agent-zero-vs-opencode.md)
- [Agent Zero vs OpenHands](https://www.anchorterminal.com/compare/agent-zero-vs-openhands.md)
- [Agent Zero vs Prime Agent](https://www.anchorterminal.com/compare/agent-zero-vs-prime-agent.md)
- [Agent Zero vs Qwen Code](https://www.anchorterminal.com/compare/agent-zero-vs-qwen-code.md)
- [Agent Zero vs Mirror CLI](https://www.anchorterminal.com/compare/agent-zero-vs-reflection-mirror.md)
- [Aider vs Harness²](https://www.anchorterminal.com/compare/aider-vs-harness2.md)
- [Amp vs Harness²](https://www.anchorterminal.com/compare/amp-vs-harness2.md)
- [Antigravity CLI vs Harness²](https://www.anchorterminal.com/compare/antigravity-cli-vs-harness2.md)
- [Claude Code vs Harness²](https://www.anchorterminal.com/compare/claude-code-vs-harness2.md)
- [Cline vs Harness²](https://www.anchorterminal.com/compare/cline-vs-harness2.md)
- [Cursor CLI vs Harness²](https://www.anchorterminal.com/compare/cursor-cli-vs-harness2.md)
- [Devin vs Harness²](https://www.anchorterminal.com/compare/devin-vs-harness2.md)
- [Droid CLI vs Harness²](https://www.anchorterminal.com/compare/droid-cli-vs-harness2.md)
- [Pi vs Harness²](https://www.anchorterminal.com/compare/earendil-pi-vs-harness2.md)
- [Gemini CLI vs Harness²](https://www.anchorterminal.com/compare/gemini-cli-vs-harness2.md)
- [GitHub Copilot CLI vs Harness²](https://www.anchorterminal.com/compare/github-copilot-cli-vs-harness2.md)
- [goose vs Harness²](https://www.anchorterminal.com/compare/goose-vs-harness2.md)
- [Harness² vs HarnessRouter](https://www.anchorterminal.com/compare/harness2-vs-harnessrouter.md)
- [Harness² vs Kilo Code CLI](https://www.anchorterminal.com/compare/harness2-vs-kilo-code-cli.md)
- [Harness² vs Kiro CLI](https://www.anchorterminal.com/compare/harness2-vs-kiro-cli.md)
- [Harness² vs Muse Code](https://www.anchorterminal.com/compare/harness2-vs-muse-code.md)
- [Harness² vs OpenAI Codex](https://www.anchorterminal.com/compare/harness2-vs-openai-codex.md)
- [Harness² vs OpenCode](https://www.anchorterminal.com/compare/harness2-vs-opencode.md)
- [Harness² vs OpenHands](https://www.anchorterminal.com/compare/harness2-vs-openhands.md)
- [Harness² vs Prime Agent](https://www.anchorterminal.com/compare/harness2-vs-prime-agent.md)
- [Harness² vs Qwen Code](https://www.anchorterminal.com/compare/harness2-vs-qwen-code.md)
- [Harness² vs Mirror CLI](https://www.anchorterminal.com/compare/harness2-vs-reflection-mirror.md)

---

Query this catalogue directly over MCP: https://www.anchorterminal.com/mcp (Streamable HTTP, no key). How: https://www.anchorterminal.com/agents/#mcp