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 instructions/lesleslie/css-mcp/claude-mdgit clone --depth 1 https://github.com/lesleslie/css-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/lesleslie/css-mcp/claude-md)<a href="https://agentmods.dev/instructions/lesleslie/css-mcp/claude-md"><img src="https://agentmods.dev/badge/instructions/lesleslie/css-mcp/claude-md.svg" alt="Measured on agentmods" 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 | $0.01577 | $0.01577 |
| Opus 5 | $0.00788 | $0.00788 |
| Sonnet 5 | $0.00315 | $0.00315 |
| Haiku 4.5 | $0.00158 | $0.00158 |
Grade A, and why
css-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 4d 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 — 166 lines — stays where its author put it; the contents beside it link to each section on GitHub.
CLAUDE.md
This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
For a shorter, tool-neutral bootstrap document, start with AGENTS.md.
Project Overview
CSS MCP Server is an MCP (Model Context Protocol) server for CSS analysis and documentation, designed for the FastBlocks ecosystem. It provides 9 tools for analyzing programmatically generated CSS from style adapters like Kelp UI and WebAwesome.
Development Commands
# Install dependencies
uv sync --group dev
# Run tests
pytest
# Type check
mypy css_mcp
# Lint
ruff check css_mcp
# Run the server locally
css-mcp
# or
python -m css_mcp.server
Architecture
The server is built on FastMCP and follows a modular architecture:
css_mcp/
├── server.py # MCP server entry point, async create_app + sync wrapper
├── tools/ # Tool implementations
│ ├── __init__.py # Pydantic input models + register_tools (all 9 tools) + register_health_tool (health probe)
│ └── profiles.py # Tool profile dispatch (W4.1, mcp-common>=0.18.0)
├── analyzer.py # Core CSS analysis engine (~150 derived metrics over 78 CSSMetrics fields)
├── mdn_fetcher.py # MDN Web Docs documentation fetcher
├── compat.py # Browser compatibility checker
├── config.py # Configuration with environment variable support
├── cli.py # Console-script entry (css-mcp) wired to mcp-common factory
├── __main__.py # `python -m css_mcp` entry point
└── __init__.py # Package metadata (CSSAnalyzer, CSSMetrics, CSSMCPSettings exports)
Key Components
CSSAnalyzer (analyzer.py): The core analysis engine that parses CSS using tinycss2 and computes ~150 derived metrics (78 CSSMetrics fields plus selector/property counters) including:
- Complexity scores (0-100)
- Specificity analysis with distribution
- Selector patterns (ID, class, element, universal)
- Property categorization (layout, typography, flexbox, grid, etc.)
- Quality metrics (duplicates, empty rules, !important usage)
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.
- 4d ago First seen · 166 lines · 1,577 tokens per session scan A 2faeee4e18d4
css-mcp CLAUDE.md is an instructions file published in the GitHub repository lesleslie/css-mcp (1 stars, last pushed 3d ago), licensed BSD-3-Clause. It adds 1,577 tokens to every session, about $0.0079 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.
Other instructions, from other repositories
vscode buildNext.instructions.md
Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).
spec-kit AGENTS.md
AGENTS.md instructions for github/spec-kit, covering agents.md, about spec kit and specify, quickstart — add a new integration in 5 steps, integration architecture and integrationmanifest — file tracking.
codex AGENTS.md
AGENTS.md instructions for openai/codex, covering rust/codex-rs, the codex-core crate, code review rules, crate api surface and model visible context.
langchain AGENTS.md
AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.
vscode oss-third-party-notices.instructions.md
Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, applying the notice (cutover) and fallback chain (never fail the build).
next.js AGENTS.md
Instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.