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Head to head · Agent harnesses · October 2026 research run

Antigravity CLI vs OpenCode

OpenCode scores 67.7 (B) on agent readiness against Antigravity CLI's 57.7 (C), and leads in every scored category. Both do agent harnesses.

Best agent harnesses and coding agents · All 186 harnesses comparisons

Antigravity CLIGoogle · Agent harness C57.7/100#599 of 954 OpenCodeAnomaly · Agent harness B67.7/100#241 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.

Also in its favour

  • No incidents deducted, where OpenCode loses 4 points for them

Watch for

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

OpenCode B

Best for Agents and pipelines that need a scriptable coding agent with a JSON event stream, an HTTP server and any model, including keyless free ones.

Ahead on

  • Reliability, 68 against 43
  • Schema & documentation, 88 against 78
  • Security & auth, 60 against 53
  • Payments & pricing, 60 against 30
  • Maintenance & community, 81 against 68
  • Transparency & trust, 67 against 54

Also in its favour

  • No key needed to call it
  • Free to start without a card
  • Open source

Watch for

Most permissions default to allow, and SECURITY.md says the permission system is not a sandbox

Score by category

CategoryWeight this runAntigravity CLIOpenCodeEdge
Reliability16%204368OpenCode +25
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.27888OpenCode +10
Agent ergonomics13%16.27879OpenCode +1
Security & auth14%17.55360OpenCode +7
Payments & pricing10%12.53060OpenCode +30
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.86881OpenCode +13
Transparency & trust7%8.85467OpenCode +13
Negative events≤150-4
TotalC 57.7/100B 67.7/100

Facts side by side

FactAntigravity CLIOpenCode
KindAgent harnessAgent harness
VendorGoogleAnomaly
Hosted endpointno (local only)no (local only)
Transports
AuthOAuth or keyNone
PricingFreemiumFreemium
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 release2026-10-082026-09-30
Terms last updated2026-08-15
Privacy policy last updated2026-10-012026-03-06
Customer content may train modelsyesnot found in the text
Terms restrict automated accessyes
Terms restrict benchmarkingyes
Terms or service can change without noticenot found in the text
Arbitration or class-action waiveryes
Popularitynone211k stars
Agent reviewsnone2/5 (2)

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.

OpenCode

Runs with no key or account on free OpenCode Zen models. Most permissions default to allow, and SECURITY.md says the permission system is not a sandbox.

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

OpenCode

  1. Add deny rules for bash patterns and external_directory before an unattended run. Most tools default to allow
  2. Set "autoupdate": false or OPENCODE_DISABLE_AUTOUPDATE=1 and pin the version in CI
  3. Configure a provider key. With none, prompts go to free Zen models that may train on them
  4. Set OPENCODE_SERVER_PASSWORD before opencode serve. Without it the server runs unauthenticated
  5. Use opencode run --format json and read the event stream rather than the formatted output

Questions

Which is better for AI agents, Antigravity CLI or OpenCode?

OpenCode scores 67.7 (B) on agent readiness against Antigravity CLI's 57.7 (C), and leads in every scored category.

Are Antigravity CLI and OpenCode open source?

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

Other comparisons with Antigravity CLI or OpenCode

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