# MCP Tool Contract Gate (`quietrelay/mcp-tool-contract-gate`) Actor

MCP server tool-contract monitor for agent platforms. Catch consumer-breaking MCP tool changes before agents break: compare an HTTPS tool catalog to a baseline and export Dataset findings, SUMMARY, SARIF, and JUnit for CI or schedules.

- **URL**: https://apify.com/quietrelay/mcp-tool-contract-gate.md
- **Developed by:** [quiet relay](https://apify.com/quietrelay) (community)
- **Categories:** Developer tools, AI, MCP servers
- **Stats:** 2 total users, 1 monthly users, 100.0% runs succeeded, 0 bookmarks
- **User rating**: No ratings yet

## Pricing

from $0.05 / mcp tool comparison completed

This Actor is paid per event. You are not charged for the Apify platform usage, but only a fixed price for specific events.

Learn more: https://docs.apify.com/platform/actors/running/actors-in-store#pay-per-event

## What's an Apify Actor?

Actors are web data automations that power AI and operations. They run on the Apify platform to scrape websites, process data, connect APIs, and automate workflows.
In Batch mode, an Actor accepts a well-defined JSON input, performs an action which can take anything from a few seconds to a few hours,
and optionally produces a well-defined JSON output, datasets with results, or files in key-value store.
In Standby mode, an Actor provides a web server which can be used as a website, API, or an MCP server.
Actors are written with capital "A".

## How to integrate an Actor?

If asked about integration, you help developers integrate Actors into their projects.
You adapt to their stack and deliver integrations that are safe, well-documented, and production-ready.
The best way to integrate Actors is as follows.

- **AI agents and MCP clients** — the [Apify MCP server](https://docs.apify.com/integrations/mcp.md) at `https://mcp.apify.com` (remote, streamable HTTP, OAuth on first use).
- **Agentic workflows and local Actor development** — [Agent Skills](https://apify.com/.well-known/agent-skills/index.json) with the [Apify CLI](https://docs.apify.com/cli/docs.md): `npm install -g apify-cli`, then `apify login`.
- **JavaScript/TypeScript projects** — the official [JS/TS client](https://docs.apify.com/api/client/js/docs.md): `npm install apify-client`.
- **Python projects** — the official [Python client](https://docs.apify.com/api/client/python/docs.md): `pip install apify-client`.
- **Any other language** — the [REST API](https://docs.apify.com/api/v2.md).

For usage examples, see the [API](#api) section below.

For more details, see Apify documentation as [Markdown index](https://docs.apify.com/llms.txt) and [Markdown full-text](https://docs.apify.com/llms-full.txt).

# README

## MCP Tool Contract Gate

Catch **consumer-breaking MCP tool contract changes** before agents and clients break.

Compare a live HTTPS MCP tool catalog (tools/list-shaped JSON) against a stored baseline and emit Dataset findings plus `SUMMARY`, `SARIF`, and `JUnit` for CI or scheduled monitoring.

### What counts as breaking

- Tool removed
- Argument newly required
- Argument removed
- Incompatible JSON Schema type/format changes
- Enum value removed
- Narrowed numeric/string bounds
- Behavioral annotation changes (`readOnlyHint`, `destructiveHint`, etc.) as warnings

Description-only edits are ignored.

### Safe defaults

- Only explicitly supplied **HTTPS** catalogs are fetched
- No credentials in v1
- Failed downloads do not overwrite baselines
- Default/demo input must stay fast and public

### Baseline modes

| Mode | Behavior |
|---|---|
| `auto` | Create the first baseline for a `monitorId`, then compare later without overwriting |
| `compareOnly` | Compare only; error if no baseline exists |
| `accept` | Write reports, then replace the stored baseline |

### Pricing

Pay per event: **MCP tool comparison completed** after successful report artifacts are written. Failed fetches/invalid catalogs are not charged for the comparison event.

### Authorization

Only analyze tool catalogs you own or are authorized to access.

Built by **Quiet Relay**.

# Actor input Schema

## `toolsUrl` (type: `string`):

HTTPS JSON document: MCP tools/list shape, {"tools":\[...]}, or a bare tool array.

## `baselineMode` (type: `string`):

Create the first baseline, explicitly accept a new one, or only compare.

## `monitorId` (type: `string`):

Stable named baseline identifier. Defaults from the tools URL in auto mode.

## `baselineToolsUrl` (type: `string`):

HTTPS baseline tool catalog for a one-off comparison.

## `toolAllowlist` (type: `array`):

Optional tool name filter. When set, only these tools are compared.

## `failOnSeverity` (type: `string`):

Highest finding severity that should fail a CI-oriented comparison.

## `requestTimeoutSecs` (type: `integer`):

Maximum HTTPS tools-document request time.

## Actor input object example

```json
{
  "toolsUrl": "https://api.apify.com/v2/key-value-stores/quietrelay~mcp-demo-fixtures/records/baseline-tools",
  "baselineMode": "auto",
  "monitorId": "mcp-demo",
  "failOnSeverity": "error",
  "requestTimeoutSecs": 20
}
```

# Actor output Schema

## `findings` (type: `string`):

Individual deterministic MCP tool-contract findings.

## `summary` (type: `string`):

Finding counts, provenance, hashes, and CI failure decision.

## `sarif` (type: `string`):

SARIF 2.1.0 report for code-scanning and CI consumers.

## `junit` (type: `string`):

JUnit XML report for build pipelines.

# API

You can run this Actor programmatically using our API. Below are code examples in JavaScript, Python, and CLI, as well as the OpenAPI specification and MCP server setup.

## JavaScript example

```javascript
import { ApifyClient } from 'apify-client';

// Initialize the ApifyClient with your Apify API token
// Replace the '<YOUR_API_TOKEN>' with your token
const client = new ApifyClient({
    token: '<YOUR_API_TOKEN>',
});

// Prepare Actor input
const input = {
    "toolsUrl": "https://api.apify.com/v2/key-value-stores/quietrelay~mcp-demo-fixtures/records/baseline-tools",
    "monitorId": "mcp-demo"
};

// Run the Actor and wait for it to finish
const run = await client.actor("quietrelay/mcp-tool-contract-gate").call(input);

// Fetch and print Actor results from the run's dataset (if any)
console.log('Results from dataset');
console.log(`💾 Check your data here: https://console.apify.com/storage/datasets/${run.defaultDatasetId}`);
const { items } = await client.dataset(run.defaultDatasetId).listItems();
items.forEach((item) => {
    console.dir(item);
});

// 📚 Want to learn more 📖? Go to → https://docs.apify.com/api/client/js/docs

```

## Python example

```python
from apify_client import ApifyClient

# Initialize the ApifyClient with your Apify API token
# Replace '<YOUR_API_TOKEN>' with your token.
client = ApifyClient("<YOUR_API_TOKEN>")

# Prepare the Actor input
run_input = {
    "toolsUrl": "https://api.apify.com/v2/key-value-stores/quietrelay~mcp-demo-fixtures/records/baseline-tools",
    "monitorId": "mcp-demo",
}

# Run the Actor and wait for it to finish
run = client.actor("quietrelay/mcp-tool-contract-gate").call(run_input=run_input)

# Fetch and print Actor results from the run's dataset (if there are any)
print("💾 Check your data here: https://console.apify.com/storage/datasets/" + run["defaultDatasetId"])
for item in client.dataset(run["defaultDatasetId"]).iterate_items():
    print(item)

# 📚 Want to learn more 📖? Go to → https://docs.apify.com/api/client/python/docs/quick-start

```

## CLI example

```bash
echo '{
  "toolsUrl": "https://api.apify.com/v2/key-value-stores/quietrelay~mcp-demo-fixtures/records/baseline-tools",
  "monitorId": "mcp-demo"
}' |
apify call quietrelay/mcp-tool-contract-gate --silent --output-dataset

```

## MCP server setup

```json
{
    "mcpServers": {
        "apify": {
            "command": "npx",
            "args": [
                "mcp-remote",
                "https://mcp.apify.com/?tools=quietrelay/mcp-tool-contract-gate",
                "--header",
                "Authorization: Bearer <YOUR_API_TOKEN>"
            ]
        }
    }
}

```

## OpenAPI specification

Download the OpenAPI definition: https://api.apify.com/v2/actors/g9QW5sN6OhfnCRwH8/builds/tsAPc2z1spBvitnuc/openapi.json