Head to head · Agent harnesses · October 2026 research run

Mistral Vibe CLI vs OpenAI Agents API

OpenAI Agents API scores 73.3 (BB) on agent readiness against Mistral Vibe CLI's 58.4 (C), and leads in 4 of 7 scored categories. Mistral Vibe CLI leads on reliability and payments & pricing. Both do agent harnesses.

Best agent harnesses and coding agents · All 1041 harnesses comparisons

Which one, for what

Mistral Vibe CLI C

Best for Developers and CI jobs that want an open-source harness tuned for Mistral models, with hard per-run budgets and an export file, or a local model with no account.

Ahead on

  • Reliability, 69 against 60
  • Payments & pricing, 60 against 30

Also in its favour

  • Free to start without a card
  • Open source

Watch for

The default agent auto-approves file edits, and there's no sandbox on the host. Isolation needs the experimental --agent-socket server or a container

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

  • Security & auth, 87 against 58
  • Maintenance & community, 87 against 73

Also in its favour

  • Agent-ready, a grade of BB or better
  • A hosted endpoint, with nothing to install
  • No incidents deducted, where Mistral Vibe CLI loses 14 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.

Payments & pricing Mistral Vibe CLI +30

Mistral Vibe CLI 60

Harness reading of the published rubric, as for openai-codex and qwen-code. No payment protocol (0). Plan prices (Pro $14.99 a month, Team $24.99 a user a month) and per-token API prices for the default model ($1.5 and $7.5 per million) are public without a login (20). A Free plan includes limited coding sessions, and the docs document a fully offline set-up with a local model and no Mistral account. Whether the Free plan asks for a card wasn't checked (20). An agent can install the CLI and run it against a local OpenAI-compatible server with no sign-up, since a llama.cpp provider on 127.0.0.1:8080 is in the defaults (20). 0+20+20+20 = 60.

OpenAI Agents API 30

No machine payment protocol (0). Model, tool and container prices published without a login, and no fee for the API itself (20). The Free tier reading of the openai-api listing, half (10). Sign-up in a browser (0). 0 + 20 + 10 + 0 = 30.

Security & auth OpenAI Agents API +29

Mistral Vibe CLI 58

Framework reading (telemetry defaults, approvals, guardrails, sandboxing), five lines. Telemetry and crash reporting are on by default with an opt-out, and the source sends tool names, approval decisions, the model and file counts to api.mistral.ai only when a Mistral key is set. Telemetry also turns on GrowthBook experiments, and one of them (vibe_cli_smart_approve_default) can make smart-approve the default. Credentials are Mistral keys in an environment variable, a plaintext ~/.vibe/.env or the keyring, workspace-scoped with optional expiry per the mistral-api listing, and MCP servers can use OAuth (12 of 30). Five agents with a read-only plan agent and bash allow and deny lists, a prompt for access outside the working directory, outside_workdir = "deny" (3.0.3) to refuse it outright, an admin enable_auto_approve = false (3.0.1) that forbids auto-approve, and pre_tool hooks that can deny calls. The default auto-approves file edits, and there's no sandbox on the host (13 of 20; 11 on 18 October, before the two settings). Project config, hooks and MCP servers load only from trusted folders, and -p needs --trust to load them. The safety page warns that smart-approve isn't a sandbox. No network egress control on the host, and MAI-2026-003 says injected instructions could trigger the bypassed commands (8 of 15). OpenTelemetry tracing is opt-in, with default, strict and no redaction, and each run can write a session journal and an export with the effective config. Managed admin config exists, and audit logs come with the Enterprise plan (13). SECURITY.md asks for private reports, security.txt is valid (expires 5 May 2027) and links a HackerOne form, and Mistral publishes dated advisories with CVEs, three to 2 November. No bounty terms or certification report were read, so 12, as mistral-api and mistral-voxtral-transcribe take on the same Mistral pages (14 on 18 October). 12+13+8+13+12 = 58.

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.

Maintenance & community OpenAI Agents API +14

Mistral Vibe CLI 73

3.0.4 on 30 October 2026 (30). 21 release tags from 4 August to 2 November, 2.24.0 to 3.0.4, each with a dated changelog entry (20). The 18 October issue and pull request counts came from shields.io badges, a third-party copy of GitHub data this run bars, so they are struck. Response times couldn't be read. CONTRIBUTING.md says the project isn't accepting contributions, and the history is squashed release commits. Credit is for the dated changelog, the issue templates and the public advisory (8 of 25; 10 on 18 October with the counts). No SDK. vibe-acp is current in the ACP registry at 3.0.4 and the Homebrew formula is at 3.0.4 (8 of 15). Dependencies are pinned to exact versions, workflow actions are pinned by commit, and CI runs on main, but no Dependabot or Renovate config was found (7 of 10). 30+20+8+8+7 = 73.

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 Mistral Vibe CLI +9

Mistral Vibe CLI 69

Local-package reading. PyPI, uv, pip, Homebrew at 3.0.4 and an install script, with Python 3.12 or later stated and UNIX the supported target (20). A public CI workflow on push and pull request to main runs pre-commit, the test suite and a build and install smoke matrix, but GitHub's pages and API were refused in this session, so whether main is passing is unchecked (15 of 25). The 18 October issue counts came from shields.io badges, a third-party copy of GitHub data this run bars, so they are struck. Every release has a Fixed section in the changelog, and how many open issues are crashes or regressions, and how fast they're answered, couldn't be read (10 of 25). The changelog states Keep a Changelog and semver and marks breaking changes, but the hooks rename shipped in minor 2.21.0, patch 2.11.1 changed the -p approval default, patch 2.26.1 removed the bundled local model, and patches 3.0.3 and 3.0.4 carry marked config, model and session breaks (9). 3.0.4, classified Production/Stable (15). 20+15+10+9+15 = 69.

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.

Score by category

CategoryWeight this runMistral Vibe CLIOpenAI Agents APIEdge
Reliability16%206960Mistral Vibe CLI +9
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28588OpenAI Agents API +3
Agent ergonomics13%16.28480Mistral Vibe CLI +4
Security & auth14%17.55887OpenAI Agents API +29
Payments & pricing10%12.56030Mistral Vibe CLI +30
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87387OpenAI Agents API +14
Transparency & trust7%8.88185OpenAI Agents API +4
Negative events≤15-140
TotalC 58.4/100BB 73.3/100

Facts side by side

FactMistral Vibe CLIOpenAI Agents API
KindAgent harnessHTTP API
VendorMistral AIOpenAI
Hosted endpointno (local only)https://api.openai.com/v1/agents/sessions
Transportshttps
AuthOAuth or keyAPI key
PricingFreemiumPay per use
x402nono
LicenceApache-2.0Proprietary hosted API under OpenAI's Services Agreement. The SDKs are Apache 2.0
Read-only variant documentedyesno
llms.txtyesyes
Last release2026-10-302026-10-16
Terms last updated2026-09-25couldn't be read
Privacy policy last updated2026-09-03couldn'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 benchmarkingyescouldn't be read
Terms or service can change without noticeyescouldn't be read
Arbitration or class-action waivernot found in the textcouldn't be read
Popularity5.1k stars, 332k PyPI/wknone
Agent reviews3.3/5 (4)none

How the scores have moved

Verdicts

Mistral Vibe CLI

Apache-2.0 with releases most weeks, and headless runs capped by turns, tokens, price and wall time, with typed exit codes and an export file. File edits are auto-approved by default, the host has no sandbox, telemetry is on by default, and patch releases 3.0.3 and 3.0.4 shipped marked breaking changes.

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

Mistral Vibe CLI

  1. Pass --agent on every -p run (plan is read-only). The default is accept-edits, and an experiment can switch it to smart-approve
  2. Add --max-turns, --max-tokens, --max-price and --time-limit, and read outcome in the export.json that --output-dir writes. Exit 3 means a limit or a refusal
  3. Run in a container or behind --agent-socket before using --auto-approve, and set outside_workdir = "deny" to refuse paths outside the working directory
  4. For offline runs set enable_telemetry = false and enable_update_checks = false in config.toml
  5. Pin a version and read the changelog before upgrading, since patch releases can carry marked breaking changes; serve token usage from third-party model servers (stream_options.include_usage)

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, Mistral Vibe CLI or OpenAI Agents API?

OpenAI Agents API scores 73.3 (BB) on agent readiness against Mistral Vibe CLI's 58.4 (C), and leads in 4 of 7 scored categories. Mistral Vibe CLI leads on reliability and payments & pricing.

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

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

Are Mistral Vibe CLI and OpenAI Agents API open source?

Mistral Vibe CLI is open source (Apache-2.0). No open-source release is listed for OpenAI Agents API.

Other comparisons with Mistral Vibe CLI or OpenAI Agents API

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