Borrowing it
Nothing to install: this file belongs to mcpwright/census-mcp. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/mcpwright/census-mcp/main/CLAUDE.mdgit clone --depth 1 https://github.com/mcpwright/census-mcpWrote 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.
[](https://agentmods.dev/instructions/mcpwright/census-mcp/claude-md)<a href="https://agentmods.dev/instructions/mcpwright/census-mcp/claude-md"><img src="https://agentmods.dev/badge/instructions/mcpwright/census-mcp/claude-md/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/instructions/mcpwright/census-mcp/claude-md"><img src="https://agentmods.dev/badge/instructions/mcpwright/census-mcp/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.01142 | $0.01142 |
| Opus 5.5 | $0.00457 | $0.00457 |
| Sonnet 5.5 | $0.00228 | $0.00228 |
| Haiku 4.5 | $0.00114 | $0.00114 |
Grade A, and why
census-mcp CLAUDE.md 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 2mo 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 — 72 lines — stays where its author put it; the contents beside it link to each section on GitHub.
census-mcp — working agreement
census-mcp is a server in the mcpwright suite (github.com/mcpwright): polished,
public MCP servers that bring a real-world data source into any agent. Every server in
the suite meets the same engineering bar, set by the reference server edgar-mcp.
Source of truth:
edgar-mcp. When a convention here is unclear, copy edgar (~/github-personal/edgar-mcp). The full written rubric is~/my-notes/professional-self-improvement/mcpwright/mcp-standards.md. To scaffold/extend to standard, use thenew-mcpwright-serverskill.
Non-negotiable policies
- Lots of unit tests. Every tool and every parser/formatter has tests. Mock all
external I/O (
respxfor HTTP; a seeded temp SQLite store for the local data). A new tool ships with its tests in the same PR.pytest -vmust be green before a PR opens. - Use the latest patterns. Official
mcpPython SDK viamcp.server.fastmcp(NOT the standalonefastmcppackage). Python 3.12+ idioms,from __future__ import annotations, pydantic v2 models with aField(description=...)on every field,uvfor deps + build, asynchttpx. Tools return typed pydantic models (structured output) and are annotatedreadOnlyHint=True. - PR per change, CI-gated. Standard flow:
feature branch → code → code-review subagent → fold in findings → PR → CI green → squash-merge.
- Code-review subagent: before opening the PR, review the diff (
git diff main...HEAD) with thecode-reviewersubagent (.claude/agents/code-reviewer.md) — or just run/review-pr. It runs in a fresh context with no memory of the coding session and returns severity-tagged findings (Blocker / High / Medium / Low). Address Blocker/High (and add a regression test for any real bug) before the PR. - Merge: the
Code Quality & Testscheck green and branch up to date → squash-merge with a(#N)suffix.mainis branch-protected; no direct pushes. - Commits: imperative subject + a short body, ending with the dual trailer
(
Co-authored-by: Devender …+Co-authored-by: Claude …). - One focused change per PR — keep process/docs changes (like this one) out of feature PRs.
- Code-review subagent: before opening the PR, review the diff (
- Green locally before pushing:
uv run ruff check src/ && uv run ruff format --check src/ && uv run mypy && uv run pytest -vuv run pre-commit run --all-filesmirrors CI (ruff, ruff-format, mypy, detect-secrets, hygiene).
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.
- 2mo ago First seen · 72 lines · 1,142 tokens per session scan A 8efd51f1b9e4
census-mcp CLAUDE.md is an instructions file published in the GitHub repository mcpwright/census-mcp (0 stars, last pushed 2mo ago), licensed MIT. It adds 1,142 tokens to every session, about $0.0046 per session on Opus 5.5. 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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