# Antigravity CLI vs Prime Agent

> Prime Agent scores 60.5 (C) to Antigravity CLI's 57.7 (C) for agent harnesses. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/antigravity-cli-vs-prime-agent
- Markdown: https://www.anchorterminal.com/compare/antigravity-cli-vs-prime-agent.md (~2,800 tokens)
- Slim: https://www.anchorterminal.com/compare/antigravity-cli-vs-prime-agent.min.md (~680 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/antigravity-cli-vs-prime-agent.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
- Updated: 2026-10-10

Prime Agent scores 60.5 (C) on agent readiness against Antigravity CLI's 57.7 (C), and leads in 4 of 7 scored categories. Antigravity CLI leads on schema & documentation and agent ergonomics. Both do agent harnesses.

- Antigravity CLI: grade C, 57.7/100, rank #599 of 954. Markdown https://www.anchorterminal.com/tools/antigravity-cli.md · JSON https://www.anchorterminal.com/api/v1/tools/antigravity-cli.json
- Prime Agent: grade C, 60.5/100, rank #512 of 954. 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 186 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:
- Schema & documentation, 78 against 42
- Agent ergonomics, 78 against 73

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

### 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 43
- Payments & pricing, 60 against 30
- Maintenance & community, 79 against 68
- Transparency & trust, 64 against 54

Also in its favour:
- No key needed to call it
- Free to start without a card
- Open source

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 | Antigravity CLI | Prime Agent | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 43 | 65 | Prime Agent +22 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 78 | 42 | Antigravity CLI +36 |
| Agent ergonomics | 13% (16.2 this run) | 78 | 73 | Antigravity CLI +5 |
| Security & auth | 14% (17.5 this run) | 53 | 50 | Antigravity CLI +3 |
| Payments & pricing | 10% (12.5 this run) | 30 | 60 | Prime Agent +30 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 68 | 79 | Prime Agent +11 |
| Transparency & trust | 7% (8.8 this run) | 54 | 64 | Prime Agent +10 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **57.7 · C** | **60.5 · C** | |

## Facts side by side

| Fact | Antigravity CLI | Prime Agent |
| --- | --- | --- |
| Kind | Agent harness | Agent harness |
| Vendor | Google | Prime Intellect |
| 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 | MIT |
| Read-only variant documented | no | no |
| llms.txt | yes | no |
| Last release | 2026-10-08 | 2026-10-07 |
| Terms last updated |  | no date given |
| Privacy policy last updated | 2026-10-01 | no date given |
| Customer content may train models | yes | 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 | none | 22k stars |

## 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.

**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

### 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

### 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, Antigravity CLI or Prime Agent?

Prime Agent scores 60.5 (C) on agent readiness against Antigravity CLI's 57.7 (C), and leads in 4 of 7 scored categories. Antigravity CLI leads on schema & documentation and agent ergonomics.

### Are Antigravity CLI and Prime Agent open source?

No open-source release is listed for Antigravity CLI. Prime Agent is open source (MIT).


## For agents

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

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