mcp-mock-server

A zero-dependency, configurable mock MCP server for testing MCP clients and harnesses. Serves a correct MCP handshake over stdio (initialize, tools/list, tools/call). You describe tools and canned responses in a JSON file. Simulates errors and missing-argument handling. Perfect target for your existing conformance, audit, and load-test tools.

{
  "mcpServers": {
    "mcp-mock-server": {
      "command": "uvx",
      "args": [
        "mcp-mock-server"
      ]
    }
  }
}

claude mcp add mcp-mock-server uvx mcp-mock-server

{
  "mcpServers": {
    "mcp-mock-server": {
      "command": "uvx",
      "args": [
        "mcp-mock-server"
      ]
    }
  }
}