Dynamic Per-User Tool Generation MCP Server

# MCP Server with Dynamic Per-User Tool Generation A Model Context Protocol (MCP) server implementation using FastMCP that dynamically generates tools based on user permissions from an external API. ## Features - **Dynamic Tool Generation**: Tools are generated at runtime based on user-specific schemas from an external API - **Per-User Permissions**: Each authenticated user receives tools tailored to their permissions - **Intelligent Caching**: Both API schemas and generated tools are cached with TTL for performance - **Graceful Degradation**: Falls back to static tools if API is unavailable - **Comprehensive Logging**: Detailed logging at INFO, DEBUG, WARNING, and ERROR levels - **Thread-Safe**: Concurrent requests from multiple users are handled safely ## Architecture ### Components 1. **`mcp_server.py`** - Main server entry point - Initializes FastMCP server - Registers static tools (add, echo, multiply) - Sets up dynamic tool middleware 2. **`api_client.py`** - External API integration - `FormSchemaClient`: Fetches and parses schemas from external API - `FormSchemaCache`: Caches API responses with TTL - Converts API field definitions to JSON Schema format 3. **`dynamic_tool_manager.py`** - Tool lifecycle management - `DynamicToolManager`: Manages per-user tool storage - Thread-safe caching with TTL - Cache statistics and invalidation 4. **`tool_function_factory.py`** - Dynamic function generation - Creates typed async functions from JSON schemas - Generates proper `inspect.Signature` for FastMCP validation - Maps JSON Schema types to Python types 5. **`tool_execution_handler.py`** - Tool execution backend - `ToolExecutionRouter`: Routes tool calls to appropriate handlers - Specialized handlers for different tool types - Structured error responses 6. **`dynamic_tool_middleware.py`** - FastMCP middleware - Intercepts `list/tools` requests - Extracts authentication tokens - Generates and caches user-specific tools - Returns combined static + dynamic tools ## Installation 1. **Install dependencies:** ```bash pip install -r requirements.txt ``` 2. **Configure the API URL:** Edit `mcp_server.py` and set the `FORM_SCHEMA_API_URL` to your external API endpoint: ```python FORM_SCHEMA_API_URL = "http://172.16.11.131/api/module/request/form" ``` ## Usage ### Starting the Server ```bash python mcp_server.py ``` The server will start on `http://127.0.0.1:9092/mcp` ### Authentication The server expects authentication via HTTP `Authorization` header: ``` Authorization: Bearer <your-token> ``` The token is used to: 1. Fetch user-specific schema from the external API 2. Generate tools with fields the user has permission to access 3. Cache tools for subsequent requests ### Available Tools #### Static Tools (Always Available) - **`add(a: int, b: int) -> int`** - Adds two numbers - **`echo(message: str) -> str`** - Echoes a message - **`multiply(a: int, b: int) -> int`** - Multiplies two numbers #### Dynamic Tools (User-Specific) - **`create_request(...)`** - Creates a request with fields based on user permissions - Parameters are dynamically generated from the external API schema - Each user sees different parameters based on their permissions - Required fields, enums, and types are enforced ## How It Works ### Request Flow 1. **Client sends `list/tools` request** with `Authorization: Bearer <token>` 2. **Middleware intercepts the request:** - Extracts auth token from header - Checks if tools are cached for this user - If cached: Returns cached tools - If not cached: Proceeds to generation 3. **Tool Generation:** - Fetches schema from external API with user's token - Parses API response into JSON Schema - Creates typed async function with proper signature - Converts function to FastMCP `Tool` object - Caches the tool for future requests 4. **Response:** - Returns list of static tools + dynamic tools - Client sees tools specific to their permissions ### Tool Execution Flow 1. **Client calls `create_request` tool** with arguments 2. **FastMCP validates arguments** against the generated function signature 3. **Tool execution handler:** - Receives validated arguments - Processes the request - Returns structured response with ID, timestamp, status ## Configuration ### Cache TTL Both schema cache and tool cache use 5-minute TTL by default. To change: ```python # In mcp_server.py schema_client = FormSchemaClient( api_url=FORM_SCHEMA_API_URL, cache_ttl=300, # Change this value (seconds) verbose=True ) tool_manager = DynamicToolManager(cache_ttl_seconds=300) # Change this value ``` ### Logging Level To change logging verbosity: ```python # In mcp_server.py logging.basicConfig( level=logging.DEBUG, # Change to DEBUG, INFO, WARNING, or ERROR format='%(asctime)s - %(name)s - %(levelname)s - %(message)s' ) ``` ## Testing See `TEST_SCENARIOS.md` for comprehensive test scenarios including: - User-specific tool generation - Caching behavior - Tool execution - Error handling - Validation enforcement ## API Schema Format The external API should return a response with this structure: ```json { "fieldList": [ { "name": "Subject", "paramName": "subject", "type": "TextFieldRest", "required": true, "description": "Request subject", "groupIds": [1, 2], "hidden": false, "removed": false, "inActive": false } ] } ``` Supported field types: - `TextFieldRest` → `string` - `NumberFieldRest` → `number` - `DropDownFieldRest` → `string` with enum - `MultiSelectDropDownFieldRest` → `array` of strings - And more (see `api_client.py` for full mapping) ## Security Considerations - Authentication tokens are truncated in logs and responses - Tokens are validated on each request - No token = static tools only (graceful degradation) - FastMCP validates all tool arguments before execution ## Troubleshooting ### Server won't start - Check that all dependencies are installed: `pip install -r requirements.txt` - Verify Python version is 3.12+ - Check logs for import errors ### Tools not appearing - Verify `Authorization` header is present and correctly formatted - Check server logs for API fetch errors - Ensure external API is accessible - Verify user has permissions in the external system ### Cache not updating - Default TTL is 5 minutes - Manually clear cache: Call `tool_manager.clear_all_tools()` or restart server - Check logs for cache hit/miss messages ## License [Your License Here] ## Contributing [Your Contributing Guidelines Here]