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Agent skill

Analyze API Contract Coverage

by cyberful in cyberful/cyberful

Deterministically compare OpenAPI JSON operations with implementation and observation inventories to expose undocumented, unimplemented, unexercised, and security-declaration coverage gaps.

AGPL-3.0Auto-check passedBackend & APIs

Install Analyze API Contract Coverage

skills CLI
$ npx skills add cyberful/cyberful --skill analyze-api-contract-coverage -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install cyberful/cyberful analyze-api-contract-coverage --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/cyberful/cyberful.git skills-src && mkdir -p .claude/skills && cp -r skills-src/cyberful/builtin/skills/analyze-api-contract-coverage .claude/skills/analyze-api-contract-coverage && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
analyze-api-contract-coverage
GitHub stars
135
Token cost
~585 tokens
SKILL.md length
167 words
Files
9 (incl. scripts, references, assets)
Skills in repo
85
Repo updated
First seen
Licence
AGPL-3.0

At a glance

Deterministically compare OpenAPI JSON operations with implementation and observation inventories to expose undocumented, unimplemented, unexercised, and security-declaration coverage gaps.

  • Offline API evidence reconciliation
  • Runs Python scripts from its folder
  • Tasks that involve API design
  • Tasks that involve OpenAPI specifications

What it does

Analyze API Contract Coverage is an agent skill from cyberful/cyberful. Deterministically compare OpenAPI JSON operations with implementation and observation inventories to expose undocumented, unimplemented, unexercised, and security-declaration coverage gaps. Use for offline API evidence reconciliation.

Its SKILL.md is about 590 tokens, which your agent loads only when the skill is triggered. The skill folder holds 13 other files, including scripts, reference files and assets (for example `agents/openai.yaml`, `assets/api-contract-coverage-evidence.schema.json` and `assets/api-contract-coverage-input.example.json`).

It sits in Backend & APIs, covering API design, OpenAPI specifications and Accounting and bookkeeping. It works with OpenAPI. The repository describes itself as: Cyberful is an open-source AI Red Team for discovering, exploiting, verifying, and remediating vulnerabilities. The licence is AGPL-3.0.

When your agent uses it

  • Offline API evidence reconciliation
  • Tasks that involve API design
  • Tasks that involve OpenAPI specifications

Example prompts

  • “/analyze-api-contract-coverage”

Requirements

  • Python 3

What it can do on your machine

Read from SKILL.md and the folder at commit ec598a6. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Ships 2 files in scripts/ (Python), which the agent can run.

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Analyze API Contract Coverage loads about 585 tokens when it runs, and up to ~938 if it reads all its reference files. Until then it costs about 66 tokens; SKILL.md has 167 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~66
When it runs · the whole SKILL.md, loaded when a task matches
~585
With references · SKILL.md plus every file in references/, read only if the agent opens them
~938

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); the scripts in this folder are not scanned.

SKILL.md

The full file from cyberful/cyberful at commit ec598a6, republished under its AGPL-3.0 licence (© cyberful). 167 words, ~585 tokens.

Download SKILL.mdSave it as .claude/skills/analyze-api-contract-coverage/SKILL.md (or your agent's skills folder). This skill also uses 8 other files; get the full folder from GitHub.
name
analyze-api-contract-coverage
description
Deterministically compare OpenAPI JSON operations with implementation and observation inventories to expose undocumented, unimplemented, unexercised, and security-declaration coverage gaps. Use for offline API evidence reconciliation.
metadata.domain
application-security
metadata.subdomain
api-contract-evidence
metadata.triggers
analyze API contract coverage, OpenAPI route coverage, compare observed operations to specification, find undocumented API endpoints, reconcile API evidence
metadata.tags
API, OpenAPI, coverage, evidence, offline-analysis

Analyze API Contract Coverage

Build a reproducible operation ledger from OpenAPI JSON and compare it with normalized implementation and observation inventories. Coverage is evidence of reconciliation, not proof that an operation is secure or reachable.

Stage scripts/analyze_api_contract_coverage.py, its manifest, the input schema, and the example. The analyzer is offline, reads only confined regular JSON files, starts no child process, and writes deterministic bounded evidence under the output schema.

Read coverage-method.md before interpreting unmatched operations or security declarations. Convert YAML to JSON with an already-authorized offline tool before staging; do not let format conversion fetch remote references.

Interpret the ledger

  • undocumented_implementation identifies registered operations absent from the selected contract set.
  • unimplemented_contract identifies declared operations absent from the implementation inventory.
  • unexercised_contract identifies declared operations absent from observation evidence.
  • explicitly_anonymous identifies operations whose effective OpenAPI security is an empty requirement; validate intent in code.

Normalize aliases and gateway rewrites before treating a difference as drift. Escalate to audit-api-contract-implementation for executable enforcement and to protocol specialists for gRPC or SOAP behavior.

© cyberful, AGPL-3.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 8 other files (scripts, references, assets) in cyberful/builtin/skills/analyze-api-contract-coverage of cyberful/cyberful.

  • SKILL.md
  • agents/openai.yaml
  • assets/api-contract-coverage-evidence.schema.json
  • assets/api-contract-coverage-input.example.json
  • assets/api-contract-coverage-input.schema.json
  • references/coverage-method.md
  • scripts/analyze_api_contract_coverage.py
  • scripts/manifest.json
  • tests/test_analyze_api_contract_coverage.py

Open the folder on GitHubat commit ec598a6

Compare with similar skills

Analyze API Contract Coverage next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Analyze API Contract Coverage compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Analyze API Contract Coverage this skillcyberful/cyberful135—~585Automated safety check: PassAGPL-3.0
Attio Upgrade Migrationjeremylongshore/tons-of-skills-marketplace2.8k—~1kAutomated safety check: PassMIT
703 Technologies Fuzzing Testingjabrena/plinth446—~874Automated safety check: PassApache-2.0
API DesignerJeffallan/claude-skills12k2 repos~2kAutomated safety check: PassMIT
Old Coder API DesignAmazingAng/old-coder7491 repos~3.4kAutomated safety check: PassMIT
API Surface Reviewpolarsource/polar10k—~1.3kAutomated safety check: PassMIT

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Works with

Categories

Questions about Analyze API Contract Coverage

What does Analyze API Contract Coverage do?

Deterministically compare OpenAPI JSON operations with implementation and observation inventories to expose undocumented, unimplemented, unexercised, and security-declaration coverage gaps. Analyze API Contract Coverage is an agent skill from cyberful/cyberful. Deterministically compare OpenAPI JSON operations with implementation and observation inventories to expose undocumented, unimplemented, unexercised, and security-declaration coverage gaps.

When should I use Analyze API Contract Coverage?

Analyze API Contract Coverage fits situations like: offline API evidence reconciliation; tasks that involve API design; tasks that involve OpenAPI specifications.

How do I install Analyze API Contract Coverage in Claude Code?

Run `npx skills add cyberful/cyberful --skill analyze-api-contract-coverage -a claude-code`. Or copy the skill folder (cyberful/builtin/skills/analyze-api-contract-coverage in cyberful/cyberful) into .claude/skills/analyze-api-contract-coverage in your project. Claude Code loads it when a task matches its description.

How do I install Analyze API Contract Coverage in Codex?

Run `npx skills add cyberful/cyberful --skill analyze-api-contract-coverage -a codex`. Or copy the skill folder (cyberful/builtin/skills/analyze-api-contract-coverage in cyberful/cyberful) into .agents/skills/analyze-api-contract-coverage in your project. Codex loads it when a task matches its description.

Can I use Analyze API Contract Coverage in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add cyberful/cyberful --skill analyze-api-contract-coverage -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/analyze-api-contract-coverage, .gemini/skills/analyze-api-contract-coverage, .github/skills/analyze-api-contract-coverage and .opencode/skills/analyze-api-contract-coverage in your project.

What does Analyze API Contract Coverage need to run?

Going by SKILL.md and its folder, Analyze API Contract Coverage needs Python for the scripts in its folder. Our summary lists: Python 3.

Does Analyze API Contract Coverage access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Analyze API Contract Coverage safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. The check reads SKILL.md only: the scripts in the folder are not scanned, so read them before running anything.

What licence does Analyze API Contract Coverage use?

Analyze API Contract Coverage is published under the AGPL-3.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Analyze API Contract Coverage use?

About 585 tokens (SKILL.md is roughly 2.3k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 353 tokens, read only when the agent opens those files.

What are the alternatives to Analyze API Contract Coverage?

Skills that share tags, products or a category with Analyze API Contract Coverage: Attio Upgrade Migration (jeremylongshore/tons-of-skills-marketplace, 2.8k stars), 703 Technologies Fuzzing Testing (jabrena/plinth, 446 stars), API Designer (Jeffallan/claude-skills, 12k stars) and Old Coder API Design (AmazingAng/old-coder, 749 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Analyze API Contract Coverage?

cyberful (a GitHub organization) maintains it in cyberful/cyberful, which has 135 GitHub stars. The repository holds 85 skills in this directory. The repository was last updated on August 24, 2026.

Source: cyberful/cyberful on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.