Head to head · Agent harnesses · October 2026 research run

Antigravity CLI vs OpenAI Agents API

OpenAI Agents API scores 73.3 (BB) on agent readiness against Antigravity CLI's 54.7 (C), and leads in 6 of 7 scored categories. Both do agent harnesses.

Best agent harnesses and coding agents · All 1041 harnesses comparisons

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.

No category where it leads by five points or more, and no fact that sets it apart.

Watch for

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

OpenAI Agents API BB

Best for Teams that want OpenAI to run the agent loop, with sandboxes, MCP tools and subagents, and are fine with a beta API, US-only data residency and no Zero Data Retention.

Ahead on

  • Reliability, 60 against 43
  • Schema & documentation, 88 against 78
  • Security & auth, 87 against 53
  • Maintenance & community, 87 against 68
  • Transparency & trust, 85 against 55

Also in its favour

  • Agent-ready, a grade of BB or better
  • A hosted endpoint, with nothing to install
  • No incidents deducted, where Antigravity CLI loses 3 points for them

Watch for

Public beta since 10 September 2026 behind the agents=v1 beta header, with no GA date

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Security & auth OpenAI Agents API +34

Antigravity CLI 53

Framework reading (credentials and telemetry defaults, approvals and sandboxing, guardrails, audit, security programme), five lines. Credentials are a Google account sign-in kept in the operating system keyring, or a Gemini API key in settings.json. The README says using the CLI allows Google to collect Interactions until the user opts out (10). Since 1.3.5 on macOS and Linux and 1.4.4 on Windows 11 24H2 the default for personal accounts is Auto mode, which runs commands in the terminal sandbox, hides ~/.ssh, .env and, since 1.4.6, ~/.docker and ~/.kube, blocks network access outside approved domains, and has a separate agent review commands that leave the sandbox. Auto approves file edits and safe commands without asking, Turbo turns the sandbox off, and business accounts start in Default (18). Hooks run before and after tool calls and can block one, and since 1.4.11 a PreInvocation hook can stop a turn. No documented defence against prompt injection in fetched content was found (7). The CLI log records model resolution, and approvals show in the conversation, but no exportable audit log was found (10). google.com has a valid security.txt with reports to g.co/vulnz (per the 10 October check), antigravity.google serves none, no CLI advisory appears in the changelog, and NVD returns no CVE for Antigravity on 4 November. The repository's advisory page couldn't be read (8). 10+18+7+10+8 = 53.

OpenAI Agents API 87

Project keys with restricted per-endpoint permissions, service accounts and workload identity, per the openai-api listing; we didn't confirm a key can be limited to /v1/agents (27 of 30). Automatic review for approvals, a sandbox network restricted to a host allowlist, vaults for secrets and a sandbox security guide (17 of 20). The agent reads web pages, MCP results and browser content; the sandbox security guide and approval flow are the mitigations, with no prompt-injection guide of its own found (8 of 15). Tracing, observability and usage per session and admin audit logs (15). SOC 2 Type 2, ISO 27001 family, Bugcrowd bounty and a disclosure policy, per the openai-api listing (20). Not ZDR-eligible and US residency only, recorded under transparency. 27 + 17 + 8 + 15 + 20 = 87.

Transparency & trust OpenAI Agents API +30

Antigravity CLI 55

Closed source, with clear terms. The binary is under the Google Antigravity Additional Terms, the Universal Terms and the Privacy Policy (15). The terms say Interactions are recorded while the Service runs and used to evaluate, develop and improve Google and Alphabet products and machine learning, that Google employees and contractors may review them, and that the user can ask for deletion by email. The README and settings page agree, but no retention period appears in the pages read (15). Dated notices exist for the Gemini CLI transition and for the removal of Claude Sonnet 4.6, Claude Opus 4.6 and GPT-OSS 120B, now set for 18 November 2026, and since 1.3.0 the CLI shows announcement cards for deprecations, but there is no written deprecation policy for the CLI (10). The README says collection is on by using the CLI with an opt-out at any time, and Enable Telemetry in /config turns it off and is always off for business accounts. The settings page no longer calls it anonymous usage statistics, but it doesn't state the default and its CLI line says only "usage data" (16, judgement call). 15+15+10+16 = 56.

OpenAI Agents API 85

Closed service with clear terms, Apache-2.0 SDKs (15). Session state retained until deleted, deletable sessions and artifacts, not ZDR-eligible, US residency only, and the data-controls guide agrees; no retention period for artifacts after a sandbox expires (25 of 30). Dated deprecation notices with minimum periods for GA models; a beta API can change faster (15 of 20). Subprocessors and processing countries listed, per the openai-api listing (20). 15 + 25 + 15 + 20 = 75.

Maintenance & community OpenAI Agents API +19

Antigravity CLI 68

1.4.12 on 30 October 2026, marked Latest in the docs changelog, 5 days before this check (30). 56 tagged releases from 1.1.11 (6 August) to 1.4.12, each with a changelog entry; 1.5.0 is tagged and in the repository changelog on 4 November but not yet in the docs changelog, so it isn't counted (20). Responsiveness rests on a public changelog, a community forum linked from the terms and the GitHub repository, but no replies could be read (8). The google-antigravity Python SDK is a separate package and no SDK for the CLI itself was found; PyPI couldn't be read on 4 November, so the line rests on the 10 October reading (10). No public CI or dependency list for the CLI, since the source is not published (0). 30+20+8+10+0 = 68.

OpenAI Agents API 87

Closed API. Last dated change 16 October 2026, Ultrafast mode and document skills (30). Four dated changelog entries in the 57 days since release, 10 September, 29 September, 9 October and 16 October (20). Changelog and help centre, as the openai-api listing reads them (12 of 15). Official SDKs carry beta.agents (15). SDK CI, per the openai-api listing (10). 30 + 20 + 12 + 15 + 10 = 87.

Reliability OpenAI Agents API +17

Antigravity CLI 43

Local-package reading. An official installer for macOS, Linux and Windows, with an Android build for Termux, that checks a SHA-512 checksum from Google's release manifest before it installs (install.sh re-read on 4 November) (20). No public CI or test suite, since the repository holds no source and no workflows, only issue templates (0). Open issues and pull requests could not be read, so the crash and regression line is unchecked (0). Behaviour changes ship in patch releases as Changed or Improved bullets with no breaking-change heading, such as 1.4.6 (23 October) closing ~/.docker and ~/.kube to sandboxed commands, and 1.2.10's exit-code change (8). Version 1.x, so stable under the rule (15). 20+0+0+8+15 = 43.

OpenAI Agents API 60

Read as a hosted API. status.openai.com has an Agents component under APIs (20). Since release on 10 September (57 days, not 90), the feed names the Agents API in a degraded-performance incident on 14 September, the elevated errors across ChatGPT, Codex and the API on 29 September (the openai-api listing reads that one as a major, 17:52 to 23:14 UTC), computer use issues and degraded workspace agents on 6 and 7 October, degraded performance across the APIs for 22 minutes on 21 October, and overbilling for hosted containers on 19 September. One major, the rest minor (10). Rate limits come from the shared guide, published per tier and model with headers, and the errors page adds a Files API allowance on session creation (15). 429 and 503 guidance with Retry-After, capped backoff and a check-then-retry procedure for turns (15). The Scale Tier SLA in the openai-api listing isn't shown to cover a beta API (0). Public beta behind the agents=v1 header (0). 20 + 10 + 15 + 15 + 0 + 0 = 60.

Schema & documentation OpenAI Agents API +10

Antigravity CLI 78

Framework reading. No published JSON Schema for settings.json, mcp_config.json or hooks.json was found, although the docs type each key (10). llms.txt at antigravity.google/llms.txt, and every docs page has a Markdown copy (10). Pages say when to use each permission preset and execution mode, what each allows and when the sandbox applies (15). Presets, modes, output formats, status values and effort levels are enumerated (13). The headless page documents the output envelope, the status values and exit codes, with a jq example (15). A dated changelog on the docs site and versioned release notes and tags in the repository (15). 10+10+15+13+15+15 = 78.

OpenAI Agents API 88

The reference is linked from the overview and the SDKs carry beta.agents types; we didn't confirm /agents/sessions in OpenAI's public OpenAPI file, so 15 of 25. llms.txt with every Agents API page and Markdown twins (10). The overview, architecture page and the agents guide that compares the Agents API, Agents SDK and Responses API say when to use it (20). Typed configuration with enumerated container sizes, network modes and environment types (13 of 15). Examples in six languages and an errors page with codes per HTTP status, turn and session (15). Dated changelog entries and a versioned beta header (15). 15 + 10 + 20 + 13 + 15 + 15 = 88.

Score by category

CategoryWeight this runAntigravity CLIOpenAI Agents APIEdge
Reliability16%204360OpenAI Agents API +17
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.27888OpenAI Agents API +10
Agent ergonomics13%16.27880OpenAI Agents API +2
Security & auth14%17.55387OpenAI Agents API +34
Payments & pricing10%12.53030even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.86887OpenAI Agents API +19
Transparency & trust7%8.85585OpenAI Agents API +30
Negative events≤15-30
TotalC 54.7/100BB 73.3/100

Facts side by side

FactAntigravity CLIOpenAI Agents API
KindAgent harnessHTTP API
VendorGoogleOpenAI
Hosted endpointno (local only)https://api.openai.com/v1/agents/sessions
Transportshttps
AuthOAuth or keyAPI key
PricingFreemiumPay per use
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 PolicyProprietary hosted API under OpenAI's Services Agreement. The SDKs are Apache 2.0
Read-only variant documentednono
llms.txtyesyes
Last release2026-10-302026-10-16
Terms last updatedno date givencouldn't be read
Privacy policy last updated2026-10-01couldn't be read
Customer content may train modelsyes, with an opt-outcouldn't be read
Terms restrict automated accessnot found in the textcouldn't be read
Terms restrict benchmarkingnot found in the textcouldn't be read
Terms or service can change without noticenot found in the textcouldn't be read
Arbitration or class-action waivernot found in the textcouldn't be read

How the scores have moved

Verdicts

Antigravity CLI

Google's terminal agent, a closed-source binary whose default Auto mode runs commands in a terminal sandbox on macOS, Linux and Windows 11, with documented headless JSON output. Interactions are collected for Google product improvement unless users opt out, a headless run exits 0 when a tool is denied, and 1.4.7 fixed a cross-user token flaw without an advisory.

OpenAI Agents API

OpenAI's hosted agent runtime, the Codex harness behind one session call, with MCP, functions, web search, computer use, subagents and sandboxes on OpenAI or your own infrastructure. Documentation, errors and SDKs are thorough. It's still public beta, can't use Zero Data Retention and keeps data in the United States only.

Before you call either

Antigravity CLI

  1. Read the status and finished_reason fields 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 /config before running on private repositories if Interactions should not be used for product improvement
  5. Grant sandbox access to ~/.docker or ~/.kube explicitly since 1.4.6 if a task needs Docker or Kubernetes credentials

OpenAI Agents API

  1. POST https://api.openai.com/v1/agents/sessions with a project key and the header OpenAI-Beta: agents=v1, or use client.beta.agents in the SDKs
  2. Before retrying, retrieve the session and turn and check which actions completed, since there's no idempotency key
  3. Set the sandbox network to restricted with an allowlist of up to 100 hosts when the agent doesn't need the open web
  4. Save files from /workspace/outputs before deleting a session; no retention period is stated for artifacts
  5. Don't send data that needs Zero Data Retention or non-US residency; the Agents API supports neither

Questions

Which is better for AI agents, Antigravity CLI or OpenAI Agents API?

OpenAI Agents API scores 73.3 (BB) on agent readiness against Antigravity CLI's 54.7 (C), and leads in 6 of 7 scored categories.

Can an agent call Antigravity CLI and OpenAI Agents API without installing anything?

No hosted endpoint is listed for Antigravity CLI. OpenAI Agents API has a hosted endpoint at https://api.openai.com/v1/agents/sessions.

Other comparisons with Antigravity CLI or OpenAI Agents API

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