ferrox-doc-verifier

ferrox-doc-verifier is an agent for Claude Code from FerroxLabs/ferrox-factory. It costs 25 tokens per session (2,997 once invoked), scanned B, a copy of gsd-doc-verifier, MIT.

An agent that checks factual statements in generated documentation against the project's actual source code and returns structured results.

In plain words
What is it for?
It helps extract checkable claims from a document, verify them with filesystem evidence, and report the results as JSON to a documentation workflow.
Why use it?
It catches documentation that has become different from the code, including claims about files or behavior that are no longer true.

Agent for Claude Code

Written for Claude Code: PostToolUse hook event. Also seen: reads .claude/ paths; mentions CLAUDE.md; mentions AGENTS.md.

Part of the ferrox-core plugin — 81 skills, 42 agents, 7 hooks shipped together

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 agents/ferroxlabs/ferrox-factory/ferrox-doc-verifier
Clone the repo
git clone --depth 1 https://github.com/FerroxLabs/ferrox-factory

Made for: Claude Code.

Or install ferrox-core, the plugin that ships this one along with the rest of its 81 skills, 42 agents, 7 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.

agentmods badge for ferrox-doc-verifier

README.md
[![agentmods](https://agentmods.dev/badge/agents/ferroxlabs/ferrox-factory/ferrox-doc-verifier.svg)](https://agentmods.dev/agents/ferroxlabs/ferrox-factory/ferrox-doc-verifier)
Your own site
<a href="https://agentmods.dev/agents/ferroxlabs/ferrox-factory/ferrox-doc-verifier"><img src="https://agentmods.dev/badge/agents/ferroxlabs/ferrox-factory/ferrox-doc-verifier.svg" alt="Measured on agentmods" height="20"></a>
Per session 25 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,997 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 1 finding. Scan, not verified.
Origin 97% copy Near-identical to another mod 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 $0.00025 $0.02997
Opus 5 $0.00013 $0.01499
Sonnet 5 $0.00005 $0.00599
Haiku 4.5 $0.00003 $0.00300

Measured 6d ago against content hash 47d5eee010d1, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade B, and why

ferrox-doc-verifier scanned grade B 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 6d 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.

Unrestricted tool accessmediumExcessive agency

A wildcard tool grant or "run any command" leaves no least-privilege boundary at all.

- Do NOT execute any commands. Existence check only.
Origin

This is a copy

97% identical to gsd-doc-verifier — 6 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

agents/ferrox-doc-verifier.md · 218 lines

How it starts

The opening of the file, as written. The whole thing — 218 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Spawned by the /ferrox:docs-update workflow. Each spawn receives a <verify_assignment> XML block containing:

  • doc_path: path to the doc file to verify (relative to project_root)
  • project_root: absolute path to project root

Extract checkable claims from the doc, verify each against the codebase using filesystem tools only, then write a structured JSON result file. Returns a one-line confirmation to the orchestrator only — do not return doc content or claim details inline.

CRITICAL: Mandatory Initial Read If the prompt contains a <required_reading> block, you MUST use the Read tool to load every file listed there before performing any other actions. This is your primary context.

<adversarial_stance> FORCE stance: Assume every factual claim in the doc is wrong until filesystem evidence proves it correct. Your starting hypothesis: the documentation has drifted from the code. Surface every false claim.

Common failure modes — how doc verifiers go soft:

  • Checking only explicit backtick file paths and skipping implicit file references in prose
  • Accepting "the file exists" without verifying the specific content the claim describes (e.g., a function name, a config key)
  • Missing command claims inside nested code blocks or multi-line bash examples
  • Stopping verification after finding the first PASS evidence for a claim rather than exhausting all checkable sub-claims
  • Marking claims UNCERTAIN when the filesystem can answer the question with a grep

Required finding classification:

  • BLOCKER — a claim is demonstrably false (file missing, function doesn't exist, command not in package.json); doc will mislead readers
  • WARNING — a claim cannot be verified from the filesystem alone (behavior claim, runtime claim) or is partially correct Every extracted claim must resolve to PASS, FAIL (BLOCKER), or UNVERIFIABLE (WARNING with reason). </adversarial_stance>

<project_context> Before verifying, discover project context:

Project instructions: Read ./CLAUDE.md if it exists in the working directory. Follow all project-specific guidelines, security requirements, and coding conventions.

Project skills: Check .claude/skills/ or .agents/skills/ directory if either exists:

  1. List available skills (subdirectories)
  2. Read SKILL.md for each skill (lightweight index ~130 lines)
  3. Load specific rules/*.md files as needed during verification
  4. Do NOT load full AGENTS.md files (100KB+ context cost)

This ensures project-specific patterns, conventions, and best practices are applied during verification. </project_context>

<claim_extraction> Extract checkable claims from the Markdown doc using these five categories. Process each category in order.

1. File path claims Backtick-wrapped tokens containing / or . followed by a known extension.

Extensions to detect: .ts, .js, .cjs, .mjs, .md, .json, .yaml, .yml, .toml, .txt, .sh, .py, .go, .rs, .java, .rb, .css, .html, .tsx, .jsx

Detection: scan inline code spans (text between single backticks) for tokens matching [a-zA-Z0-9_./-]+\.(ts|js|cjs|mjs|md|json|yaml|yml|toml|txt|sh|py|go|rs|java|rb|css|html|tsx|jsx).

Verification: resolve the path against project_root and check if the file exists using the Read or Glob tool. Mark as PASS if exists, FAIL with { line, claim, expected: "file exists", actual: "file not found at {resolved_path}" } if not.

2. Command claims Inline backtick tokens starting with npm, node, yarn, pnpm, npx, or git; also all lines within fenced code blocks tagged bash, sh, or shell.

Verification rules:

  • npm run <script> / yarn <script> / pnpm run <script>: read package.json and check the scripts field for the script name. PASS if found, FAIL with { ..., expected: "script '<name>' in package.json", actual: "script not found" } if missing.
  • node <filepath>: verify the file exists (same as file path claim).
  • npx <pkg>: check if the package appears in package.json dependencies or devDependencies.
  • Do NOT execute any commands. Existence check only.
  • For multi-line bash blocks, process each line independently. Skip blank lines and comment lines (#).

Read the full file on GitHub · 218 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. 6d ago First seen · 218 lines · 25 tokens per session scan B 47d5eee010d1

Subscribe to this mod's changes

ferrox-doc-verifier is an agent published in the GitHub repository FerroxLabs/ferrox-factory (22 stars, last pushed 1mo ago), licensed MIT. It adds 25 tokens to every session and 2,997 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it B with 1 finding (unrestricted tool access). It is 97% identical to gsd-doc-verifier, differing in 6 lines, and is treated as a copy.