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/jansenanalytics/claudex/api-testernpx skills add JansenAnalytics/claudex --skill api-testergit clone --depth 1 https://github.com/JansenAnalytics/claudexWhat 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 | $0.00043 | $0.00626 |
| Opus 5 | $0.00022 | $0.00313 |
| Sonnet 5 | $0.00009 | $0.00125 |
| Haiku 4.5 | $0.00004 | $0.00063 |
Grade A, and why
api-tester scanned grade A with 0 findings 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 2d 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.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
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-tester
Systematic REST and GraphQL API endpoint testing: happy path, error cases, auth flows, rate limits, schema validation. Use when: testing backend APIs, validating endpoint responses, checking error handling, verifying auth/permissions, or benchmarking API performance.
Scripts
api-test.py
Run API tests from a JSON test spec. Reports pass/fail with response details.
# From file
python3 scripts/api-test.py --spec tests.json
# From stdin
echo '{"base_url":"https://httpbin.org","tests":[{"name":"get","method":"GET","path":"/get","expect_status":200}]}' | python3 scripts/api-test.py
Test spec format:
{
"base_url": "http://localhost:3000",
"default_headers": { "Authorization": "Bearer TOKEN" },
"tests": [
{
"name": "list users",
"method": "GET",
"path": "/api/users",
"expect_status": 200,
"expect_json": { "type": "object" }
},
{
"name": "create user",
"method": "POST",
"path": "/api/users",
"headers": { "Content-Type": "application/json" },
"body": { "name": "Test", "email": "[email protected]" },
"expect_status": 201,
"expect_json": { "required": ["id", "name"] }
}
]
}
expect_json validation: type (array/object/string), required (list of keys that must exist), properties (nested type checks).
api-spec-gen.sh
Generate a test spec skeleton from Express/Fastify route files.
bash scripts/api-spec-gen.sh --source ./routes --output api-tests.json
api-benchmark.py
Performance benchmarking for API endpoints.
python3 scripts/api-benchmark.py --url https://httpbin.org/get --count 50 --concurrency 5
python3 scripts/api-benchmark.py --url http://localhost:3000/api/health --method GET --count 100 --concurrency 10 --headers '{"Authorization":"Bearer tok"}'
Reports: min, max, avg, median, p95, p99, throughput (req/s).
References
references/rest-testing-patterns.md— CRUD lifecycle, auth flows, pagination, error responsesreferences/api-checklist.md— API quality checklist: status codes, error format, CORS, input validation
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.
- 2d ago First seen · 79 lines · 43 tokens per session scan A 67d92dc5be51
api-tester is a skill published in the GitHub repository JansenAnalytics/claudex (5 stars, last pushed 2mo ago), licensed MIT. It adds 43 tokens to every session and 626 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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