What do I need to use API Test Plan?

The API; Contract; Auth & rules; Dependencies & data.

Is API Test Plan free to use?

Yes — run it free in the browser playground (no API key needed for the sponsored trial, or bring any provider key), or install it into Claude Code, Cursor, ChatGPT and more via npx pm-claude-skills. MIT-licensed and open source.

API Test Plan

Q: How do I know the API Test Plan output is good?

The skill verifies itself against its own quality checks: Each endpoint is tested beyond 200 — error codes (4xx/5xx) and their bodies are asserted; Auth and authorization cases are included (no token, expired, wrong scope/role); Validation/boundary/negative cases cover missing, invalid, and extra inputs; Responses are checked against the schema/contract, incl. backward compatibility.

🔵 Stable🕐 updated 2026-10-06 ✅ 4.8/5 🔷 SkillSpec L3 pm-qa

Plan tests for an API endpoint or service — functional, negative, and contract. Use when asked to test an API, write API test cases, plan REST/GraphQL endpoint testing, or validate an API contract. Produces an API test plan — per-endpoint cases (status codes, schema, auth, validation, errors), boundary/negative cases, contract checks, and non-functional notes — so the API is verified beyond the happy 200.

▶ Run it free — no key needed 📝 Grade your existing draft ⬇ Add to Claude (works in Duet) 📱 Use as an app View SKILL.md ↗ What changed

🗣 Say this to your agent

“Test an API.”“Write API test cases.”“Plan REST/GraphQL endpoint testing.”“Validate an API contract.”

What to give it

▸The API — REST/GraphQL, the endpoints/operations, and what they do.

▸Contract — request/response schemas, parameters, status codes (or an OpenAPI/spec if available).

▸Auth & rules — the auth model (token/scopes/roles), rate limits, and validation rules.

▸Dependencies & data — downstream services, and the data/state needed to test.

✅ The bar it holds itself to

Every skill in this library self-verifies — these are this skill's own quality checks, straight from its definition.

✓Each endpoint is tested beyond 200 — error codes (4xx/5xx) and their bodies are asserted

✓Auth and authorization cases are included (no token, expired, wrong scope/role)

✓Validation/boundary/negative cases cover missing, invalid, and extra inputs

✓Responses are checked against the schema/contract, incl. backward compatibility

✓Status codes match the spec and are used correctly (e.g. 401 vs. 403, 400 vs. 422)

✓Non-functional aspects (rate limits, pagination, data leakage) are noted

⚠️ What it refuses to do

Do not test only the happy 200 — most API bugs are in validation, auth, and error paths

Do not ignore the response schema — a 200 with the wrong body still breaks clients

Do not skip authz (role/scope) testing — "logged in" isn't "allowed"

Do not assert only status codes — check the body/contract too

Do not overlook error-body quality and correct status semantics (401 vs 403, 400 vs 404)

Install

npx pm-claude-skills add --agent claude   # or codex · cursor · gemini · hermes
# or one-line MCP (every skill, any client):
claude mcp add pm-skills -- npx -y -p pm-claude-skills pm-claude-skills-mcp

Related skills

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💬 Discussion

API Test Plan is one of 1326 open-source professional AI agent skills — all SkillSpec L3. Try them all in the browser · ⭐ Star on GitHub · Browse the full catalog