What is mcpfs CLAUDE.md?

A command-line tool that mounts an MCP server—the service that provides tools and data to an AI agent—as files and folders on your computer. It also exposes operations that change data through commands.

Use it to connect to MCP servers over local or HTTP connections, view their resources as files, look up records through folders, and run create, update, delete, search, or query operations from the command line.

It lets you inspect MCP data with ordinary file tools while keeping data-changing actions explicit. This can make unfamiliar MCP services easier to explore and script.

How airshelf/mcpfs configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to airshelf/mcpfs. 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/airshelf/mcpfs/main/CLAUDE.md

Clone the repo

git clone --depth 1 https://github.com/airshelf/mcpfs

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/airshelf/mcpfs/claude-md/github.svg)](https://agentmods.dev/instructions/airshelf/mcpfs/claude-md)

Your own site

<a href="https://agentmods.dev/instructions/airshelf/mcpfs/claude-md"><img src="https://agentmods.dev/badge/instructions/airshelf/mcpfs/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.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/airshelf/mcpfs/claude-md"><img src="https://agentmods.dev/badge/instructions/airshelf/mcpfs/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 833 This file is loaded in full into every session.

When invoked 833 The same file — it is already loaded in full.

Security scan B 1 finding. A grade says what 26 rules found in the file — not that it is safe.

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	$0.00833	$0.00833
Opus 5.5	$0.00333	$0.00333
Sonnet 5.5	$0.00167	$0.00167
Haiku 4.5	$0.00083	$0.00083

Measured 2mo ago against content hash dec8dde3058f, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade B, and why

mcpfs CLAUDE.md 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 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.

Reads agent configuration directoriesmediumAgent snooping

.claude/, .codex/, .gemini/ hold keys, settings and other credentials a mod has no legitimate need for.

4. `~/.claude/settings.json` → `enabledPlugins` — enabled plugins (cache scan)

CLAUDE.md · 80 lines

How it starts

The opening of the file, as written. The whole thing — 80 lines — stays where its author put it; the contents beside it link to each section on GitHub.

mcpfs

Mount any MCP server as a FUSE filesystem. Classifies tools into reads (files) and writes (CLI).

Quick start

go build -o mcpfs ./cmd/mcpfs   # build
go test ./...                    # test
go vet ./...                     # lint

Architecture

pkg/mcpclient/ — MCP JSON-RPC client (stdio + HTTP transports)
pkg/mcptool/ — Tool schema → CLI bridge. Parses JSON Schema into flags, dispatches calls.
internal/fuse/ — FUSE filesystem. Maps resources → files, templates → dirs.
internal/toolfs/ — Tool classification (list/get/create/update/delete/search/query)
internal/config/ — servers.json parser with env interpolation
cmd/mcpfs/ — CLI: mount, auto-discover, tool proxy, unmount

How it works

mcpfs connects to any MCP server, classifies its tools, and exposes reads as files:

list_*, get_all_*, no required params → file (dashboards.json)
get_*, retrieve_*, has required params → directory (lookup by ID)
create_*, update_*, delete_* → CLI only (mcpfs tool)
search_*, query_* → CLI only (mcpfs tool)

Resources (if the server has them) are also mounted as files.

Commands

mcpfs auto                              # discover Claude Code plugins, mount to .mcpfs/
mcpfs auto --json                       # dry run — show discovered config
mcpfs auto --mount /custom/dir          # mount to custom dir
mcpfs .mcpfs/posthog --http <url>       # mount single HTTP server
mcpfs .mcpfs/stripe -- npx -y @stripe/mcp  # mount single stdio server
mcpfs tool posthog                      # list tools for a server
mcpfs tool posthog create-flag --key x  # call a write tool
mcpfs -u .mcpfs/posthog                 # unmount

Project-local mounts

mcpfs auto mounts to .mcpfs/ in the current directory (project-local). Reads .env.local and .env from cwd for project-specific credentials, then falls back to ~/.config/mcpfs/env.

Different projects can have different API keys for the same services.

Read the full file on GitHub · 80 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.

2mo ago First seen · 80 lines · 833 tokens per session scan B dec8dde3058f

Subscribe to this mod's changes

mcpfs CLAUDE.md is an instructions file published in the GitHub repository airshelf/mcpfs (4 stars, last pushed 8mo ago), licensed MIT. It adds 833 tokens to every session, about $0.0033 per session on Opus 5.5. A static security scan graded it B with 1 finding (reads agent configuration directories). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Building agents agent-experience ai-agents cli developer-tools devtools

mcpfs CLAUDE.md next to 6 instructions from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
mcpfs CLAUDE.mdairshelf/mcpfs	Instructions file	4	8mo ago	MIT	B	833	Claude Code
vscode buildNext.instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	9,719	GitHub Copilot
next.js AGENTS.mdvercel/next.js	Instructions file	143k	yesterday	MIT	A	7,461	Codex, OpenCode
langchain AGENTS.mdlangchain-ai/langchain	Instructions file	149k	yesterday	MIT	A	4,680	Codex, OpenCode
vscode oss-third-party-notices.instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	5,516	GitHub Copilot
vscode copilot-instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	3,093	GitHub Copilot
deepseek-harness AGENTS.mddeepseek-ai/deepseek-harness	Instructions file	274k	2d ago	MIT	A	4,313	Codex, OpenCode

mcpfs: Instructions file for Claude Code