MCP Hook Conformance

Name: MCP Hook Conformance
Author: studiomeyer-io

by studiomeyer-ioversion 0.1.3i★ –iRuns on your computer

Registry nameio.studiomeyer/hook-conformance

Install

Overview

Description from the maker (original English)

Audits MCP servers for Claude Code mcp_tool hook readiness: idempotency, latency, side-effects.

PopNx MCP’s three pillars

These three are never merged into one score: opinions, measurements and popularity are different things.

User voiceiNo reviews yetReviews open together with accounts in a later step
Our basic checksi1 of 1 passedChecked from public information; code not scanned yet
UsageiNot measured yet★ –

What you can do with it

We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.

Connection: Runs on your computer
Transport: stdio
Category: Other

Install

Pick the AI app you use, then copy the settings.

Before you install

Basic checks: 1 of 1 passed
Runs on your computer with your user’s permissions (files, network, apps).
The registry lists no key to fill in.

You need

npmNode.js installed (for the npx command)

Which app do you use?

ClaudeClaude CodeCursorVS CodeChatGPT

Pick your app above. We remember it, so next time the button says “Install in …”.

Open Claude Desktop → Settings → Developer → Edit Config, and paste this into claude_desktop_config.json

{
  "mcpServers": {
    "hook-conformance": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-hook-conformance"
      ]
    }
  }
}

Run this in your terminal

claude mcp add hook-conformance -- npx -y mcp-hook-conformance

Open in Cursor

Or copy the settings yourself

Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json

{
  "mcpServers": {
    "hook-conformance": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-hook-conformance"
      ]
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

Open in VS Code

Or copy the settings yourself

Paste into .vscode/mcp.json in your project

{
  "servers": {
    "hook-conformance": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "mcp-hook-conformance"
      ]
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

This one runs on your computer, and ChatGPT can only connect to servers on the internet. Pick another app.

Your choice stays on this device in a cookie; no account needed.

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

What it can do

Runs on your computer; the tool list appears in your AI app after you install it.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 6, 2026

✓ Pass
Maker matches the repo
The registry name was verified against the domain studiomeyer.io (the registry checks domain ownership)
… Not checked yet
Still maintained
We have not read this repo from GitHub yet
… Not checked yet
Has a licence
We have not read this repo from GitHub yet
– Not applicable
Endpoint responds
This one runs on your computer; there is no internet endpoint
– Not applicable
Sign-in with OAuth
Runs on your computer and uses local settings instead
… Not checked yet
No hidden instructions in tool descriptions
Runs on your computer; we can only read tool lists from internet endpoints

Compared with others in Otheri

More stars than 0% of the other 32466 servers in this category
Published to the registry more recently than 27% of the other 32466 servers in this category
Basic checks equal to or better than 100% of the other 32466 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Common questions

Is MCP Hook Conformance safe?

It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.

What keys or codes does it need?

The registry does not list a required key, though some servers ask you to sign in on first use.

Does it run on my computer or in the cloud?

It runs on your computer. Your AI app starts it when needed, and data does not pass through the maker’s servers (unless it calls an online service itself).

Is it still maintained?

The GitHub repo last changed –, and the latest version (0.1.3) reached the registry 3 months ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. You also need Node.js on your computer.

What can I use instead?

In the same category: Spec Driven Development, Remote Desktop Commander, HotCodePush

Alternatives

Servers in the same category from other makers, sorted by stars.

Reading a card:★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi

Spec Driven Development

by formulahendry

MCP Server that facilitates spec-driven development workflows, not just Vibe Coding.

Runs on your computer★ 440MITUpdated 14 months ago

Install

Remote Desktop Commander

by desktop-commander

Remote Desktop Commander: use files, terminal and processes on your own computers from any AI app.

Runs in the cloud★ 211Updated yesterday

Install

HotCodePush

by hotcodepush-team

Manage over-the-air (OTA) updates for React Native, Expo, Capacitor and Cordova apps.

Runs in the cloudUpdated today

Install

README from the maker

Open the README

Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.

Part of the [StudioMeyer MCP Stack](https://studiomeyer.io) — Built in Mallorca 🌴 · ⭐ if you use it

mcp-hook-conformance

Test-harness CLI that audits any MCP server for Claude Code v2.1.118 mcp_tool lifecycle-hook readiness.

The third foundation pillar:

mcp-protocol-conformance says: does the server speak the protocol?
mcp-server-attestation says: who signed this server?
mcp-hook-conformance says: is it safe to call this tool from a Stop, PreCompact, or UserPromptSubmit hook?

A note from us

We have been building tools and systems for ourselves for the past two years. The fact that this repo is small and has few stars is not because it is new. It is because we only just decided to share what we have built. It is not a fresh experiment, it is a long story with a recent commit.

We love building things and sharing them. We do not love social media tactics, growth hacks, or chasing stars and followers. So this repo is small. The code is real, it gets used, issues get answered. Judge for yourself.

If it helps you, sharing, testing, and feedback help us. If it could be better, an issue is more useful. If you build something with it, tell us at hello@studiomeyer.io. That genuinely makes our day.

From a small studio in Palma de Mallorca.

Install

npm install -g mcp-hook-conformance

Or run without install:

npx mcp-hook-conformance check ./hook-conformance.config.json

Quick start

# 1. Scaffold a config

npx mcp-hook-conformance init --server-name my-mcp-server

2. Edit hook-conformance.config.json (point command/args at your server)

3. Run the audit

npx mcp-hook-conformance check ./hook-conformance.config.json

Exit codes:

0 audit passed (no FAILs)
1 audit produced at least one FAIL
2 config error (missing file, invalid schema, unknown suite name)

Subcommands

Subcommand	Args	Description
`check`	` [--output=human\	json\	junit] [--suite=...] [--tool= ] [--tries= ]`	Run audit; emits report to stdout.
`init`	`[--server-name= ] [--force]`	Write example `hook-conformance.config.json` to cwd.
`explain`		Print full explanation and remediation for a finding (e.g. `IDEMP-001`).
`version-info`	—	Print tool version and supported MCP-spec range. (Alias: `version`.)

This is a CLI, not an MCP server. Do NOT run mcp-hook-conformance via mcp-inspector — the package declares mcp.specVersion for the targets it audits, not because it speaks MCP itself. Inspector will EACCES on dist/index.js (which is the library export) by design.

Audit suites

Suite	What it checks	Weight
`idempotency`	Same input N times produces same output, no UUIDs/timestamps unless annotated.	30
`side-effects`	Read-only tools must not mutate server state. Requires `stateProbe` config.	25
`latency`	p50 < 30s, p95 < 60s (configurable). 5 samples after 1 warmup call.	20
`determinism`	Response shape stable across calls; no float drift.	15
`dsgvo`	Tool description mentions data flow / retention / deletion (whole-word heuristic).	10

Suite scoring: PASS = 100, WARN = 60, INDETERMINATE = 50, FAIL = 0. Tool score = weighted average across configured suites. Aggregate score = mean of tool scores.

Config format

"$schema": "https://studiomeyer-io.github.io/mcp-hook-conformance/config.schema.json", "server": { "name": "my-mcp-server", "transport": "stdio", "command": "npx", "args": ["-y", "my-mcp-server"], "env": {} }, "suites": ["idempotency", "latency", "determinism", "side-effects", "dsgvo"], "tries": 3, "thresholds": { "latencyP50Ms": 30000, "latencyP95Ms": 60000 }, "probes": [ { "name": "search_things", "args": { "query": "audit-fixed-input" }, "stateProbe": { "tool": "list_things", "args": {} } } ], "toolFilter": ["search_things", "get_thing"] }

probes lets you pin specific arguments per tool and (for read-only tools) a stateProbe so the side-effects suite can detect mutations. Without a stateProbe the side-effects suite returns INDETERMINATE for that tool.

Finding codes

Code	Suite	Severity	Title
IDEMP-001	idempotency	FAIL	Tool output diverges across identical calls
IDEMP-002	idempotency	WARN	Response contains timestamps without `nondeterministic` annotation
IDEMP-003	idempotency	WARN	Response contains UUID/random IDs without `nondeterministic` annotation
LAT-001	latency	FAIL	Tool exceeded p95 latency budget
LAT-002	latency	WARN	Tool p50 latency above 30 seconds
DET-001	determinism	FAIL	Floating-point output drift between calls
DET-002	determinism	WARN	Response shape varies between calls
SIDE-001	side-effects	FAIL	Read-only tool produced state delta
SIDE-002	side-effects	INDETERMINATE	No state-probe configured for side-effect detection
DSGVO-001	dsgvo	FAIL	Destructive tool lacks deletion / retention documentation
DSGVO-002	dsgvo	WARN	Tool description missing data-flow keywords

Run mcp-hook-conformance explain for full remediation text.

Compatibility

Component	Version
MCP spec	2025-06-18
Claude Code	>= 2.1.118 (mcp_tool lifecycle hooks)
Node	>= 20.0.0
`@modelcontextprotocol/sdk`	^1.29.0

Tested transports:

stdio (primary)
HTTP streamable (experimental, audit semantics same as stdio)

Reference smoke tests

The tests/smoke/ suite runs the audit against production tenants of mcp-nex and mcp-crm. Opt-in:

RUN_SMOKE_TESTS=1 npm run test:smoke

Snapshot drift triggers a manual review, not a CI fail.

Limitations (read these)

Side-effect detection is not hermetic. Without a stateProbe we cannot black-box prove a read-only tool is pure. We return INDETERMINATE instead of false-positive FAIL.
Latency is end-to-end stdio roundtrip. Includes JSON-RPC framing, not pure compute.
DSGVO suite is keyword heuristic. It catches missing docs reliably; "looks compliant" is not legal advice.
No auto-fix. This tool reports findings; you fix them.

About StudioMeyer

StudioMeyer is an AI and design studio based in Palma de Mallorca, working with clients worldwide. We build custom websites and AI infrastructure for small and medium businesses. Production stack on Claude Agent SDK, MCP and n8n, with Sentry, Langfuse and LangGraph for observability and an in-house guard layer.

MCP Hook Conformance

Overview

PopNx MCP’s three pillars

What you can do with it

Install

Before you install

What it can do

Basic checksi

Maker matches the repo

Still maintained

Has a licence

Endpoint responds

Sign-in with OAuth

No hidden instructions in tool descriptions

Compared with others in Otheri

Common questions

Alternatives

Spec Driven Development

Remote Desktop Commander

HotCodePush

README from the maker

mcp-hook-conformance

A note from us

Install

Quick start

2. Edit hook-conformance.config.json (point command/args at your server)

3. Run the audit

Subcommands

Audit suites

Config format

Finding codes

Compatibility

Reference smoke tests

Limitations (read these)

About StudioMeyer

License