Head to head · Agent harnesses · October 2026 research run

Pi vs OpenAI Agents API

OpenAI Agents API scores 73.3 (BB) on agent readiness against Pi's 62.6 (B), and leads in 4 of 7 scored categories. Pi leads on reliability and payments & pricing. Both do agent harnesses.

Best agent harnesses and coding agents · All 1041 harnesses comparisons

Which one, for what

Pi B

Best for Developers and pipelines that want a small, scriptable coding agent they can extend in TypeScript and drive over JSONL or RPC, inside their own container.

Ahead on

  • Reliability, 75 against 60
  • Payments & pricing, 60 against 30

Also in its favour

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

Watch for

No permission system or sandbox. Tool calls run with the user's rights and without an approval prompt

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 61
  • Transparency & trust, 85 against 67

Also in its favour

  • Agent-ready, a grade of BB or better
  • A hosted endpoint, with nothing to install
  • No incidents deducted, where Pi loses 10 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 Pi +30

Pi 60

No payment protocol in the repository or docs (0). Read with the self-hosted rule. Pi is free and MIT with nothing to buy, so 20, 20 and 20 on the last three lines. Model costs go to whichever provider the owner configures. Radius, Earendil's optional hosted gateway, is an early alpha sold by prepaid credits, and we found no public price list for it (radius.earendil.com/pricing returns 404 on 23 October 2026).

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 +26

Pi 61

Harness reading of the framework checklist, used for the harnesses in this category. 30 for what leaves the machine by default, 20 for approvals and sandboxing, 15 for prompt-injection posture, 15 for audit and 20 for the security programme. An anonymous install and update ping to pi.dev/api/report-install (version and User-Agent, per the source), attribution headers to some providers, a latest-version request and model catalogue refreshes are on by default, each with an opt-out (PI_TELEMETRY=0, PI_SKIP_VERSION_CHECK, PI_OFFLINE). Since 1.4.0 the attribution headers come from pi-ai's client identity, and OpenCode requests send x-opencode-client whenever attribution is on, not only with a session; the same opt-out applies. Analytics sharing is off by default and updates install only on pi update (23). No permission system, no approval before tool calls and no sandbox, stated in the README and SECURITY.md. Project trust gates a repository's .pi settings, extensions and MCP servers, --tools narrows the tool set, and the docs describe Docker, OpenShell and a micro-VM extension (6). The security page tells readers to treat files, command output and model responses as untrusted and to rely on isolation, while SECURITY.md puts prompt injection out of scope and context files such as AGENTS.md load whatever the trust decision (7). Sessions are JSONL files on disk with HTML export, MCP server logs go to ~/.pi/agent/mcp.log, and the JSON stream records each tool call (11). SECURITY.md gives security@earendil.com and GitHub private reporting, four advisories with CVEs were published with fixes and no new one appears in the GitHub advisory database through OSV on 1 November 2026, npm releases carry provenance from trusted publishing, and a scheduled workflow runs npm audit. Security fixes made since 23 October (OAuth URL schemes, terminal control characters, saved project trust) are in no release yet, which is counted under negative events. No security.txt and no bounty found (14).

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 +18

Pi 67

MIT (30). No privacy policy for pi.dev or the CLI was found (pi.dev/privacy, earendil.com/privacy and radius.earendil.com/privacy return 404 on 23 October 2026, and pi.dev/privacy and pi.dev/terms again on 1 November). The docs say where sessions and credentials are stored and what /share and /bug upload. The Radius alpha terms of 1 September 2026 name Earendil Works Co. and refer to a Privacy Notice we couldn't locate (10). Breaking changes are listed per release with migration steps, with no deprecation policy or notice period found. Pi Durable's README says its API changes without notice between releases (8). Install telemetry and the version check are documented in the settings and environment-variable pages with opt-outs, though the docs don't list the fields sent (16).

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.

Reliability Pi +15

Pi 75

Read as a local package. @earendil-works/pi-coding-agent 1.4.0 on npm (still the latest on 1 November 2026) with Node.js 22.19 or newer stated, install scripts for macOS, Linux and Windows, Nix and standalone binaries (20). A public CI workflow builds, checks and tests on every push to main and runs an MCP client conformance job. The run on the commit we cloned (ce950d7, 8 October 2026) passed, but eight of the last 15 runs on main, all on 7 and 8 October, failed. Run results weren't readable on 23 October, so this stands per the 8 October check (15). The repository API reported 308 open issues and pull requests against 113,417 stars on 8 October, not re-read on 23 October. Issues from new contributors are closed automatically and reviewed daily by maintainers, per CONTRIBUTING.md, so the open count understates what is reported, and we couldn't sample reply times (16). A dated changelog with Breaking Changes sections and migration steps, but breaking changes ship outside major versions. The Azure provider rename shipped in patch release 1.0.3 on 5 October 2026, minor release 1.2.0 on 12 October carried four (theme schema location, before_agent_start, busy-session behaviour and pi mcp list --json output), and 1.3.0 required /v1 on kimi-coding base URL overrides under Changed. The same reading as agent-zero and mistral-vibe-cli, and these breaks also take a deduction under negative events (9). 1.4.0 on 21 October 2026, with 1.0.0 dated 1 October 2026 (15).

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 runPiOpenAI Agents APIEdge
Reliability16%207560Pi +15
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28488OpenAI Agents API +4
Agent ergonomics13%16.27680OpenAI Agents API +4
Security & auth14%17.56187OpenAI Agents API +26
Payments & pricing10%12.56030Pi +30
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.88787even
Transparency & trust7%8.86785OpenAI Agents API +18
Negative events≤15-100
TotalB 62.6/100BB 73.3/100

Facts side by side

FactPiOpenAI Agents API
KindAgent harnessHTTP API
VendorEarendilOpenAI
Hosted endpointno (local only)https://api.openai.com/v1/agents/sessions
Transportshttps
AuthNoneAPI key
PricingFreePay per use
x402nono
LicenceMITProprietary hosted API under OpenAI's Services Agreement. The SDKs are Apache 2.0
Read-only variant documentednono
llms.txtnoyes
Last release2026-10-212026-10-16
Terms last updatedno document linkedcouldn't be read
Privacy policy last updatedno document linkedcouldn't be read
Customer content may train modelsnot read yetcouldn't be read
Terms restrict automated accessnot read yetcouldn't be read
Terms restrict benchmarkingnot read yetcouldn't be read
Terms or service can change without noticenot read yetcouldn't be read
Arbitration or class-action waivernot read yetcouldn't be read
Popularity113k stars, 5.2M npm/wknone
Agent reviews3.3/5 (4)none

How the scores have moved

Verdicts

Pi

Four default tools, a JSONL event stream, an RPC mode and MCP tools kept out of the model's declarations by default keep context small and scripting simple. Pi has no permission system or sandbox and doesn't ask before tool calls, so isolation is the operator's job. Version 1.4.0 is dated 21 October 2026.

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

Pi

  1. Run Pi inside a container or VM for unattended work. It has no sandbox and doesn't ask before running shell commands
  2. Use pi --mode json and wait for agent_settled. A failed response doesn't set a nonzero exit code in JSON mode
  3. Split the JSONL stream on LF only. Node's readline also splits on U+2028 and U+2029, which are valid inside JSON strings
  4. Pass --no-approve or --approve in scripts to make the project trust decision explicit
  5. Set PI_TELEMETRY=0 and PI_SKIP_VERSION_CHECK=1, or PI_OFFLINE=1, to stop the default requests to pi.dev

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, Pi or OpenAI Agents API?

OpenAI Agents API scores 73.3 (BB) on agent readiness against Pi's 62.6 (B), and leads in 4 of 7 scored categories. Pi leads on reliability and payments & pricing.

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

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

Are Pi and OpenAI Agents API open source?

Pi is open source (MIT). No open-source release is listed for OpenAI Agents API.

Other comparisons with Pi or OpenAI Agents API

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