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.
npx agentmods add skills/tommymorgan/claude-plugins/api-testing-patternsnpx skills add tommymorgan/claude-plugins --skill api-testing-patternsgit clone --depth 1 https://github.com/tommymorgan/claude-pluginsWhat 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 | $0.00057 | $0.01865 |
| Opus 5 | $0.00028 | $0.00932 |
| Sonnet 5 | $0.00011 | $0.00373 |
| Haiku 4.5 | $0.00006 | $0.00186 |
Grade A, and why
API Testing Patterns 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 yesterday.
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.
curl -H "Authorization: Bearer <token>" https://api.example.com/endpoint How it starts
The opening of the file, as written. The whole thing — 347 lines — stays where its author put it; the contents beside it link to each section on GitHub.
API Testing Patterns
Purpose
Provide systematic patterns for autonomous API exploratory testing. Guide agents through comprehensive API testing including endpoint discovery, request/response validation, authentication verification, error handling checks, and security testing.
Core Testing Methodology
API Discovery Strategy
Discover API endpoints through multiple methods:
1. OpenAPI/Swagger Specification
- Parse spec to extract all endpoints
- Understand request/response schemas
- Identify authentication requirements
- Note documented error codes
2. Common Pattern Discovery
- Probe common API paths (/api/, /v1/, /graphql)
- Try standard REST conventions (GET /users, POST /users, etc.)
- Check for API documentation endpoints (/docs, /swagger, /openapi.json)
3. Undocumented Endpoint Detection
- Compare discovered endpoints with spec
- Report endpoints found but not documented (security concern)
- Note missing endpoints that should exist
Comprehensive Testing Coverage
Test each endpoint across multiple dimensions:
HTTP Methods:
- GET: Read operations
- POST: Create operations
- PUT/PATCH: Update operations
- DELETE: Delete operations
- OPTIONS: CORS preflight
Response Codes:
- 200/201: Success scenarios
- 400: Bad request (invalid input)
- 401: Unauthorized (missing/invalid auth)
- 403: Forbidden (insufficient permissions)
- 404: Not found (non-existent resources)
- 500: Server errors
Input Variations:
- Valid data (happy path)
- Invalid data types
- Missing required fields
- Boundary values (empty, very long, negative)
- Malicious inputs (SQL injection, XSS attempts)
Authentication Testing
Common Authentication Patterns
Bearer Token:
curl -H "Authorization: Bearer <token>" https://api.example.com/endpoint
API Key:
curl -H "X-API-Key: <key>" https://api.example.com/endpoint
Basic Auth:
curl -u username:password https://api.example.com/endpoint
Authentication Tests
What ships with it
3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- yesterday First seen · 347 lines · 57 tokens per session scan A f3ca73b2c7b3
API Testing Patterns is a skill published in the GitHub repository tommymorgan/claude-plugins (4 stars, last pushed 1mo ago), licensed MIT. It adds 57 tokens to every session and 1,865 once invoked, about $0.0003 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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