truss-contract-monitor-mcp

MCP server contract monitoring — detect schema drift, breaking changes, and behavioral regressions in MCP servers.

[](https://www.npmjs.com/package/truss-contract-monitor-mcp) [](LICENSE)

Contract Monitor connects to any MCP server, snapshots its tool schemas as signed hashes, and alerts you when the contract changes. It covers:

• Schema drift — tool input schemas changed
• Breaking changes — tools removed, required params removed or type-changed
• Behavioral regressions — golden tests that check response structure even when schema is unchanged
• Status badges — shields.io badges for your README

| Tool | Description | |---|---| | monitor_schema | Connect to a server and store a contract snapshot | | diff_contracts | Compare two snapshots — what changed? | | check_drift | Live check: is the server drifting from its last snapshot? | | run_golden_test | Run a golden prompt and validate response shape | | list_monitors | List all monitored servers and their status | | add_monitor | Register a new MCP server | | remove_monitor | Deregister a server | | generate_badge | Generate a shields.io badge URL |

State is stored at ~/.truss/contract-monitor/state.json.

npm install -g truss-contract-monitor-mcp

{
  "mcpServers": {
    "contract-monitor": {
      "command": "npx",
      "args": ["-y", "truss-contract-monitor-mcp"]
    }
  }
}

Or if installed globally:

{
  "mcpServers": {
    "contract-monitor": {
      "command": "truss-contract-monitor"
    }
  }
}

{
  "mcpServers": {
    "contract-monitor": {
      "command": "npx",
      "args": ["-y", "truss-contract-monitor-mcp"]