What is fxkit-mcp CLAUDE.md?

Project instructions and an MCP server guide for FxKit, a C# functional-programming library. It describes the library, its design, development workflow, documentation, and assistant tools.

Use it when working with FxKit to search its documentation and retrieve code examples or guidance about its components.

It gives an AI assistant project-specific information instead of making it guess how the library works.

How taxfyle/fxkit-mcp configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to taxfyle/fxkit-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.

Copy the file

curl -O https://raw.githubusercontent.com/taxfyle/fxkit-mcp/develop/CLAUDE.md

Clone the repo

git clone --depth 1 https://github.com/taxfyle/fxkit-mcp

Made for: Claude Code.

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.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/taxfyle/fxkit-mcp/claude-md.svg)](https://agentmods.dev/instructions/taxfyle/fxkit-mcp/claude-md)

Your own site

<a href="https://agentmods.dev/instructions/taxfyle/fxkit-mcp/claude-md"><img src="https://agentmods.dev/badge/instructions/taxfyle/fxkit-mcp/claude-md.svg" alt="Measured on agentmods" height="20"></a>

Per session 2,067 This file is loaded in full into every session.

When invoked 2,067 The same file — it is already loaded in full.

Security scan A 0 findings. Scan, not verified.

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.

Model	Per session	Once invoked
Fable 5.1	$0.02067	$0.02067
Opus 5	$0.01033	$0.01033
Sonnet 5	$0.00413	$0.00413
Haiku 4.5	$0.00207	$0.00207

Measured 6d ago against content hash ff035dbfeb45, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

fxkit-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 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.

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.

CLAUDE.md · 304 lines

How it starts

The opening of the file, as written. The whole thing — 304 lines — stays where its author put it; the contents beside it link to each section on GitHub.

FxKit MCP Server - AI Assistant Guide

Project Overview

fxkit-mcp is a Model Context Protocol (MCP) server that provides comprehensive documentation and assistance for the FxKit C# functional programming library. It dynamically fetches documentation from the official FxKit documentation site and exposes it through MCP resources, tools, and prompts for AI assistants.

Technology Stack: TypeScript, Node.js, MCP SDK, Cheerio for HTML parsing, Zod for validation

Architecture & Design

Core Components

Documentation Fetcher (src/fetcher/docs-fetcher.ts)
- Dynamically fetches content from https://taxfyle.github.io/FxKit/
- Implements 5-minute TTL cache for performance optimization
- Extracts and parses HTML content using Cheerio
- Identifies code examples and formats them for consumption
MCP Server (src/server.ts)
- Resources: 12 documentation sections
  - Introduction, Getting Started
  - Core types: Option, Result, Validation, Unit
  - Compiler services: Overview, EnumMatch, Union, Lambda, Transformer
  - Testing utilities
- Tools: 3 interactive tools
  - search_documentation: Full-text search across all docs
  - get_examples: Retrieve code examples for specific features
  - list_packages: List available NuGet packages
- Prompts: 4 pre-configured patterns
  - Convert nullable to Option
  - Railway-oriented programming
  - Validation for multiple errors
  - Generate union types
Type System (src/types.ts)
- Strongly typed interfaces for documentation structure
- Support for code examples, API references, and search results

Development Workflow

Initial Setup

npm install          # Install dependencies
npm run build        # Compile TypeScript to JavaScript

Development Commands

npm run dev          # Run with tsx for hot-reload development
npm run build        # Compile TypeScript (tsc)
npm start            # Run compiled server from dist/

Read the full file on GitHub · 304 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.

6d ago First seen · 304 lines · 2,067 tokens per session scan A ff035dbfeb45

Subscribe to this mod's changes

fxkit-mcp CLAUDE.md is an instructions file published in the GitHub repository taxfyle/fxkit-mcp (0 stars, last pushed 1y ago), licensed MIT. It adds 2,067 tokens to every session, about $0.0103 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.

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fxkit-mcp: Instructions file for Claude Code