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Head to head · Agent harnesses · October 2026 research run

Antigravity CLI vs 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. Both do agent harnesses.

Best agent harnesses and coding agents · All 186 harnesses comparisons

Antigravity CLIGoogle · Agent harness C57.7/100#599 of 954 Prime AgentPrime Intellect · Agent harness C60.5/100#512 of 954

Which one, for what

Antigravity CLI C

Best 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

Best 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

CategoryWeight this runAntigravity CLIPrime AgentEdge
Reliability16%204365Prime Agent +22
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.27842Antigravity CLI +36
Agent ergonomics13%16.27873Antigravity CLI +5
Security & auth14%17.55350Antigravity CLI +3
Payments & pricing10%12.53060Prime Agent +30
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.86879Prime Agent +11
Transparency & trust7%8.85464Prime Agent +10
Negative events≤1500
TotalC 57.7/100C 60.5/100

Facts side by side

FactAntigravity CLIPrime Agent
KindAgent harnessAgent harness
VendorGooglePrime Intellect
Hosted endpointno (local only)no (local only)
Transports
AuthOAuth or keyNone
PricingFreemiumFree
x402nono
LicenceProprietary. 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 PolicyMIT
Read-only variant documentednono
llms.txtyesno
Last release2026-10-082026-10-07
Terms last updatedno date given
Privacy policy last updated2026-10-01no date given
Customer content may train modelsyesnot found in the text
Terms restrict automated accessyes
Terms restrict benchmarkingyes
Terms or service can change without noticeyes
Arbitration or class-action waiveryes
Popularitynone22k 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).

Other comparisons with Antigravity CLI or Prime Agent

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