# ToolFit by YourAITools – MCP Server Change Monitor

> ToolFit by YourAITools – MCP Server Change Monitor is a paid API for AI agents from api.youraitools.co, paid per call via x402, $0.25/call, status unknown (last checked 2026-10-25).

Registers a public remote MCP server URL for 24-hour periodic re-auditing over 30 days, delivering HMAC-signed webhook notifications whenever the server's tool fingerprint, grade, or reachability changes.

## Facts

- Endpoint: POST https://api.youraitools.co/toolfit/v1/watch?utm_source=zero.xyz
- Price: $0.25/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-25
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/toolfit-by-youraitools-mcp-server-change-monitor-80d75ff2
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_fAqn6onon83mnONxSo5qM

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability toolfit-by-youraitools-mcp-server-change-monitor-80d75ff2 -d '<json body>'
```

Example prompt: Set up 24-hour monitoring for my MCP server at https://api.example.com/mcp and send signed change notifications to my webhook at https://hooks.example.com/mcp-alerts whenever its tool fingerprint, grade, or reachability changes.

## When to prefer this

Use this endpoint when you need continuous, scheduled monitoring of a public remote MCP server and want push-based (webhook) alerts rather than polling it yourself. It is specifically designed for MCP server tool-list fingerprinting and grading, making it more targeted than general HTTP uptime monitors. Prefer it when you care about tool inventory drift, server quality grade changes, or reachability events over a 30-day window with HMAC-verified notifications.

## Known failure modes

- Unreachable MCP server URL at registration time — watch is created but baseline cannot be established
- Webhook URL is not publicly reachable on port 443 — notifications will fail silently; registration still succeeds
- Invalid or non-HTTPS URL provided — request rejected
- Watch expires after 30 days and no further checks are made
- Payment of $0.25 USDC not processed — endpoint returns 402 Payment Required
- Signing secret lost after initial response — cannot be retrieved again

## How this service works

MCP server monitoring API (24h checks, 30 days). Register a public remote MCP server URL and an https webhook: ToolFit re-audits the server every 24 hours for 30 days and POSTs an HMAC-SHA256 signed JSON notification when its tools/list fingerprint (pin) or grade changes, or it becomes unreachable or recovers. Returns watch_id, the signing secret (shown once) and the baseline. Unreachable URLs, blocked URLs or webhooks and a full watch list are never charged.

## Output

Returns a watch_id, a one-time HMAC-SHA256 signing secret (whsec_ prefix, 64 hex chars), the baseline fingerprint pin, grade letter, numeric score, tool count, an expiry timestamp 30 days out, and a status_url for checking the watch record. Subsequent change events are delivered asynchronously via signed POST to the provided webhook.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "description": "Public remote MCP server URL (Streamable HTTP, https), e.g. https://api.youraitools.co/mcp/hub. ToolFit only lists its tools."
  },
  "every": {
   "enum": [
    "24h"
   ],
   "type": "string",
   "description": "Optional; this route is the 24 h interval (POST /v1/watch/6h for every 6 h)."
  },
  "webhook": {
   "type": "string",
   "description": "Your https endpoint (public host, port 443) that receives the signed JSON change notifications. A query string is allowed."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "every": "24h",
  "secret": "whsec_<64 hex, shown once>",
  "baseline": {
   "pin": "ts_0123456789abcdef0123456789abcdef",
   "grade": "B",
   "score": 85,
   "tools": 36
  },
  "watch_id": "w_0123456789abcdef01234567",
  "expires_at": "2026-11-23T17:00:00.000Z",
  "status_url": "https://api.youraitools.co/toolfit/v1/watch/w_0123456789abcdef01234567"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/toolfit-by-youraitools-mcp-server-change-monitor-80d75ff2/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.youraitools.co](https://www.zero.xyz/host/api.youraitools.co/llms.txt)