A manual workflow for checking an API endpoint, which is a URL that an application exposes for sending or retrieving data.

Use it to test valid requests, authentication and permission failures, invalid inputs, missing resources, boundary values, and other edge cases.

It verifies that an endpoint returns the expected status, headers, response format, and useful errors instead of checking only whether the request succeeds.

api-test — Skill for Claude Code and Codex by ao92265: A manual workflow for checking an API endpoint, which…

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods

npx agentmods add skills/ao92265/claude-code-playbook/api-test

Any agent

npx skills add ao92265/claude-code-playbook --skill api-test

Clone the repo

git clone --depth 1 https://github.com/ao92265/claude-code-playbook

Made for: Claude Code, Codex.

Or install playbook, the plugin that ships this one along with the rest of its 49 skills, 4 hooks.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/ao92265/claude-code-playbook/api-test.svg)](https://agentmods.dev/skills/ao92265/claude-code-playbook/api-test)

Your own site

<a href="https://agentmods.dev/skills/ao92265/claude-code-playbook/api-test"><img src="https://agentmods.dev/badge/skills/ao92265/claude-code-playbook/api-test.svg" alt="Measured on agentmods" height="20"></a>

Per session 82 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 655 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 1 finding. Scan, not verified.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5	$0.00082	$0.00655
Opus 5	$0.00041	$0.00328
Sonnet 5	$0.00016	$0.00131
Haiku 4.5	$0.00008	$0.00065

Measured 4d ago against content hash d07699220b2c, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

api-test scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

Triggers: "test api", "api test", "test endpoint", "check endpoint", "curl".

skills/api-test/SKILL.md · 79 lines

How it starts

The opening of the file, as written. The whole thing — 79 lines — stays where its author put it; the contents beside it link to each section on GitHub.

API Endpoint Testing

Interactive testing of API endpoints with validation of responses.

Steps

Identify the endpoint:
- URL, HTTP method, required headers
- Authentication: Bearer token, API key, cookie, or none
- Request body format: JSON, form data, multipart
- Expected response: status code, content type, shape
Test the happy path:
- Send a request with valid inputs
- Verify: status code matches expected (200, 201, etc.)
- Verify: response body shape matches API contract
- Verify: response headers are correct (Content-Type, CORS, caching)
- Record the response time
Test error cases:
- Missing required fields → expect 400 Bad Request
- Invalid data types → expect 400 or 422
- Missing authentication → expect 401 Unauthorized
- Insufficient permissions → expect 403 Forbidden
- Non-existent resource → expect 404 Not Found
- Verify error response includes helpful message
Test edge cases:
- Empty strings, null values, zero, negative numbers
- Very long strings (boundary testing)
- Special characters and unicode
- Empty arrays and objects
- Pagination boundaries (page 0, page beyond last)
Test idempotency (for mutating endpoints):
- Send the same POST/PUT request twice
- Does it create duplicates? (it shouldn't for idempotent operations)
- Does the response change on the second call?

Report results:

## API Test Results — [ENDPOINT]

| Test | Expected | Actual | Status |
|------|----------|--------|--------|
| Happy path | 200 | 200 | PASS |
| Missing auth | 401 | 401 | PASS |
| Invalid body | 400 | 500 | FAIL |
| ...          | ... | ... | ...    |

Response time: Xms
Issues found: Y

Important

Use curl or the project's HTTP client — don't install extra tools.
Don't test against production unless the user explicitly says to.
Mask sensitive data in output (tokens, passwords, PII).
Test one endpoint at a time — keep the scope focused.
Record response times but don't treat them as benchmarks — local testing != production performance.

Read the full file on GitHub · 79 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

4d ago First seen · 79 lines · 82 tokens per session scan A d07699220b2c

Subscribe to this mod's changes

api-test is a skill published in the GitHub repository ao92265/claude-code-playbook (10 stars, last pushed 17d ago), licensed MIT. It adds 82 tokens to every session and 655 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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api-test