passmcp

passmcp-server

passmcp, the Model Context Protocol server diagnostic, as MCP tools — so an agent can evaluate a server, or check an attestation about one, from inside the editor. Read-only, allowlisted, and it never sends a credential.

Contents

Getting started

• Install — release archives, go install, make install, the container image, and an MCP host configuration
• Requirements — passmcp itself, and the Go floor to build from source
• Quick Start — ask the agent to evaluate a local server

The passmcp-server ecosystem

• The passmcp-server ecosystem — passmcp, passmcp-reporting, passmcp-server, passmcp-action, passmcp-graph, passmcp-registry, passmcp-lsp, passmcp-census, satellion.com

Library reference

• Capabilities at a glance — the current surface by theme
• Ecosystem comparison — short matrix; full table at docs/COMPARISON.md
• Benchmarks — headline numbers; full table at docs/BENCHMARKS.md
• Features — the allowlist, no credentials, read-only
• Configuration — two flags and their environment variables
• Examples — tool calls and results

Operational

• When not to use passmcp-server — limitations
• Development — make targets, the install contract, CI
• Security — what an agent can and cannot make it do
• Documentation — all reference docs
• Stability guarantees — tool names, arguments and results
• License

Install

passmcp_check runs the passmcp program. passmcp must be installed and on `PATH`, or named with `--passmcp`, for that tool to work; the container image carries it. passmcp_verify_attestation needs nothing but passmcp-server.

As a Go program

go install satellion.com/passmcp-server/cmd/passmcp-server@v0.0.8

go install satellion.com/passmcp/cmd/passmcp@v0.0.8

Release binaries for Linux, macOS and Windows on amd64 and arm64 are on the releases page, with signed checksums and SLSA provenance.

From source, with make install

git clone https://github.com/sebastienrousseau/passmcp-server

cd passmcp-server make install PREFIX="$HOME/.local"

make install builds the binary and its bash, zsh and fish completions and installs them under PREFIX (default /usr/local), staged under DESTDIR when a packager sets it. make uninstall removes them. The GNUmakefile holds the contract, and CI checks the staged tree on every push.

As a container image

docker pull ghcr.io/sebastienrousseau/passmcp-server:0.0.8

The image is passmcp's own release image with passmcp-server added: distroless, non-root, linux/amd64 and linux/arm64, with passmcp at /usr/local/bin/passmcp and passmcp-server started with --passmcp pointing at it.

In an MCP host

passmcp-server speaks MCP over stdio, so a host starts it as a child process. For Claude Desktop (claude_desktop_config.json), Claude Code (.mcp.json) and other hosts that read an mcpServers block:

{

"mcpServers": { "passmcp": { "command": "passmcp-server", "args": ["--allow", ".internal.example.com"] } } }

With the container image instead:

{

"mcpServers": { "passmcp": { "command": "docker", "args": ["run", "-i", "--rm", "ghcr.io/sebastienrousseau/passmcp-server:0.0.8"] } } }

Inside a container, loopback is the container itself. To evaluate a server on the host, run the container with --network host on Linux, or point at host.docker.internal and add -e PASSMCP_SERVER_ALLOW=host.docker.internal to the arguments.

The server is listed in the official MCP Registry as com.sebastienrousseau/passmcp-server; server.json is that listing.

Requirements

The Go floor is raised only when a release needs a language feature, on a patch release like everything else pre-1.0, and the changelog says so.

Quick Start

go install satellion.com/passmcp-server/cmd/passmcp-server@v0.0.8

go install satellion.com/passmcp/cmd/passmcp@v0.0.8 claude mcp add passmcp -- passmcp-server

Then, with an MCP server of your own listening on http://127.0.0.1:3000/mcp, ask the agent:

Evaluate my MCP server at http://127.0.0.1:3000/mcp with passmcp and fix what fails.

The agent calls passmcp_check, which runs passmcp check http://127.0.0.1:3000/mcp --auth none --output json and returns the score, the grade and every failing check with its detail and a link to the fix. Loopback needs no configuration; any other host must be named with --allow first.

The passmcp-server ecosystem

Every component is released at 0.0.8 and moves in lockstep: one version across the family, released together (docs/ecosystem.md).

This repository is the distribution surface: its deliverable is a registry listing, so passmcp is where agents look for tools. It wraps passmcp's release, so its version is passmcp's latest, exactly; make lockstep checks that, make family checks this repository's row in the family manifest, and make versions checks that every file naming the version, and the passmcp-reporting module in go.mod, agree on it.

Capabilities at a glance

Ecosystem comparison

The alternative is running passmcp in a terminal and pasting the report in