fossa-api-audit

fossa-api-audit is a skill for Claude Code, Codex from darthzen/fossa-mcp. It costs 99 tokens per session (3,876 once invoked), scanned A, original, Apache-2.0.

A FOSSA API audit tool that compares the documented API, the tools registered in the server code, and the endpoints that work live. FOSSA is a service that reports software dependencies, vulnerabilities, and licenses through an API.

In plain words
What is it for?
Use it to build an API coverage matrix, test read endpoints, inspect missing or mismatched tools, and verify that write operations are refused without making an HTTP request.
Why use it?
These three views can drift apart: documentation may change, code may expose different tools, and live access depends on the current organization and token. The audit shows what is documented, implemented, and actually reachable.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to build an API coverage matrix, test read endpoints, inspect missing or mismatched tools, and verify that write operations are refused without making an HTTP request.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/darthzen/fossa-mcp/fossa-api-audit
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.

Any agent
npx skills add darthzen/fossa-mcp --skill fossa-api-audit
Clone the repo
git clone --depth 1 https://github.com/darthzen/fossa-mcp

Made for: Claude Code, Codex.

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.

agentmods badge for fossa-api-audit

README.md
[![agentmods](https://agentmods.dev/badge/skills/darthzen/fossa-mcp/fossa-api-audit.svg)](https://agentmods.dev/skills/darthzen/fossa-mcp/fossa-api-audit)
Your own site
<a href="https://agentmods.dev/skills/darthzen/fossa-mcp/fossa-api-audit"><img src="https://agentmods.dev/badge/skills/darthzen/fossa-mcp/fossa-api-audit.svg" alt="Measured on agentmods" height="20"></a>
Per session 99 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,876 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.
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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00099 $0.03876
Opus 5 $0.00049 $0.01938
Sonnet 5 $0.00020 $0.00775
Haiku 4.5 $0.00010 $0.00388

Measured 8d ago against content hash d42ac879ca88, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

fossa-api-audit 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 8d 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.

curl -s -H "Authorization: Bearer $FOSSA_API_TOKEN" \
skills/fossa-api-audit/SKILL.md · 308 lines

How it starts

The opening of the file, as written. The whole thing — 308 lines — stays where its author put it; the contents beside it link to each section on GitHub.

fossa-api-audit

Parse the vendored spec, derive the registered tool surface from the code as it sits on disk, cross them into a coverage matrix, exercise every read endpoint against the live API, run the refusal tests to prove the write gate holds, and report the gaps.

Why this workflow exists: three surfaces drift independently. The vendored spec (spec/fossa-openapi.json) is regenerated from FOSSA's published swagger and grows on FOSSA's schedule; the registered tool list changes per branch — this repo has had 9 tools on one branch and 13 on another at the same time, with tool modules that exist but are not imported; and the live API answers for what actually works today, for this org, with this token. An audit that hardcodes any of the three answers a question nobody asked.

The honest framing, stated up front and never dropped: "live-verified" means one successful call, from one org, at one moment. And the spec cannot always be failed against: some GET operations give you nothing to compare a 200 against — at 4.34.55 that is 4 of 157, counting the 3 that document no 200 response at all plus GET /projects/{locator} (the known worst case), whose 200 schema is an object with zero properties — so a live response full of fields the spec never mentions is a spec gap to report, not a server bug to flag. Keep the two verdicts separate everywhere they appear.

Run from the repo root. Results are branch-specific — name the branch (git branch --show-current) in the report, first line.

1. Enumerate the documented surface

Confirm the spec exists before anything else. It lives at spec/fossa-openapi.json on the branches where this skill is used (api-parity, security-policy-writes) but not on every branch — if the file is missing, read it out of git without switching branches, and point SPEC at the copy — every snippet in this skill reads $SPEC, which defaults to the checked-in path:

git show api-parity:spec/fossa-openapi.json > "$TMPDIR/fossa-openapi.json"
export SPEC="$TMPDIR/fossa-openapi.json"

Read the full file on GitHub · 308 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.

  1. 8d ago First seen · 308 lines · 99 tokens per session scan A d42ac879ca88

Subscribe to this mod's changes

fossa-api-audit is a skill published in the GitHub repository darthzen/fossa-mcp (1 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 99 tokens to every session and 3,876 once invoked, about $0.0005 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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