feat(mcp): enhance FastMCP server integration with multi-transport support and update CLI options

docs/mcp-integration.md

@@ -81,12 +81,23 @@ Validate a structure configuration YAML file.
 
 ## Usage
 
-### Starting the MCP Server
+### Starting the MCP Server (FastMCP stdio / http / sse)
 
-To start the MCP server for stdio communication:
+The MCP server uses FastMCP (v2.0+) and can run over stdio, http, or sse transports.
 
+- stdio (default):
 ```bash
-struct mcp --server
+struct mcp --server --transport stdio
+```
+
+- HTTP (StreamableHTTP):
+```bash
+struct mcp --server --transport http --host 127.0.0.1 --port 9000 --path /mcp
+```
+
+- SSE:
+```bash
+struct mcp --server --transport sse --host 0.0.0.0 --port 8080 --path /events
 ```
 
 ### Command Line Integration
@@ -140,10 +151,10 @@ For Cline (VS Code extension), add to your `.cline_mcp_settings.json`:
 
 ### Custom MCP Client Integration
 
-For any MCP-compatible client, use these connection parameters:
+For any MCP-compatible client, connect over stdio with your preferred SDK:
 
 ```javascript
-// Node.js example
+// Node.js example (MCP JS SDK)
 import { StdioClientTransport } from '@modelcontextprotocol/sdk/client/stdio.js';
 import { Client } from '@modelcontextprotocol/sdk/client/index.js';
 
@@ -166,7 +177,7 @@ await client.connect(transport);
 ```
 
 ```python
-# Python example
+# Python example (MCP Python SDK)
 import asyncio
 from mcp import ClientSession, StdioServerParameters
 from mcp.client.stdio import stdio_client
@@ -181,12 +192,11 @@ async def main():
         async with ClientSession(read, write) as session:
             await session.initialize()
 
-            # List available tools
             tools = await session.list_tools()
-            print(f"Available tools: {[tool.name for tool in tools.tools]}")
+            print([t.name for t in tools.tools])
 
-            # Call a tool
             result = await session.call_tool("list_structures", {})
+            # FastMCP tools return plain text content
             print(result.content[0].text)
 
 if __name__ == "__main__":
@@ -308,7 +318,8 @@ Then configure your MCP client:
 
 ### Step 1: Install struct with MCP support
 ```bash
-pip install struct[mcp]  # or pip install struct && pip install mcp
+pip install fastmcp>=2.0
+# (your MCP client may also require installing the MCP SDK, e.g., `pip install mcp`)
 ```
 
 ### Step 2: Test MCP server

requirements.txt

@@ -11,4 +11,4 @@ google-cloud
 google-api-core
 cachetools
 pydantic-ai
-mcp
+fastmcp>=2.0

struct_module/commands/mcp.py

@@ -4,35 +4,97 @@
 from struct_module.mcp_server import StructMCPServer
 
 
-# MCP command class for starting the MCP server
+# MCP command class for starting the MCP server (FastMCP stdio only)
 class MCPCommand(Command):
     def __init__(self, parser):
         super().__init__(parser)
-        parser.description = "MCP (Model Context Protocol) support for struct tool"
+        parser.description = "MCP (Model Context Protocol) using FastMCP transports (stdio, http, sse)"
         parser.add_argument('--server', action='store_true',
-                          help='Start the MCP server for stdio communication')
+                          help='Start the MCP server')
+        parser.add_argument('--transport', choices=['stdio', 'http', 'sse'], default='stdio',
+                          help='Transport protocol for the MCP server (default: stdio)')
+        # HTTP/SSE options
+        parser.add_argument('--host', type=str, default='127.0.0.1', help='Host to bind for HTTP/SSE transports')
+        parser.add_argument('--port', type=int, default=8000, help='Port to bind for HTTP/SSE transports')
+        parser.add_argument('--path', type=str, default='/mcp', help='Endpoint path for HTTP/SSE transports')
+        parser.add_argument('--uvicorn-log-level', dest='uvicorn_log_level', type=str, default=None,
+                          help='Log level for the HTTP server (e.g., info, warning, error)')
+        parser.add_argument('--stateless-http', action='store_true', default=None,
+                          help='Use stateless HTTP mode (HTTP transport only)')
+        parser.add_argument('--no-banner', dest='show_banner', action='store_false', default=True,
+                          help='Disable FastMCP startup banner')
+        # Debugging options
+        parser.add_argument('--debug', action='store_true', help='Enable debug mode (sets struct and FastMCP loggers to DEBUG by default)')
+        parser.add_argument('--fastmcp-log-level', dest='fastmcp_log_level', type=str, default=None,
+                          help='Log level for FastMCP internals (e.g., DEBUG, INFO). Overrides --debug for FastMCP if provided')
         parser.set_defaults(func=self.execute)
 
     def execute(self, args):
         if args.server:
-            self.logger.info("Starting MCP server for struct tool")
-            asyncio.run(self._start_mcp_server())
+            self.logger.info(
+                f"Starting FastMCP server for struct tool (transport={args.transport})"
+            )
+            asyncio.run(self._start_mcp_server(args))
         else:
-            print("MCP (Model Context Protocol) support for struct tool")
+            print("MCP (Model Context Protocol) support for struct tool (FastMCP)")
             print("\nAvailable options:")
-            print("  --server    Start the MCP server for stdio communication")
+            print("  --server                 Start the MCP server")
+            print("  --transport {stdio|http|sse}  Transport protocol (default: stdio)")
+            print("  --host HOST              Host for HTTP/SSE (default: 127.0.0.1)")
+            print("  --port PORT              Port for HTTP/SSE (default: 8000)")
+            print("  --path /PATH             Endpoint path for HTTP/SSE (default: /mcp)")
+            print("  --stateless-http         Enable stateless HTTP mode (HTTP only)")
+            print("  --no-banner              Disable FastMCP banner")
+            print("  --debug                  Enable debug mode (struct + FastMCP DEBUG; uvicorn=debug)")
+            print("  --fastmcp-log-level LVL  Set FastMCP logger level (overrides --debug for FastMCP)")
             print("\nMCP tools available:")
             print("  - list_structures: List all available structure definitions")
             print("  - get_structure_info: Get detailed information about a structure")
             print("  - generate_structure: Generate structures with various options")
             print("  - validate_structure: Validate structure configuration files")
-            print("\nTo integrate with MCP clients, use: struct mcp --server")
+            print("\nExamples:")
+            print("  struct mcp --server --transport stdio --debug")
+            print("  struct mcp --server --transport http --host 127.0.0.1 --port 9000 --path /mcp --uvicorn-log-level debug")
+            print("  struct mcp --server --transport sse --host 0.0.0.0 --port 8080 --path /events --fastmcp-log-level DEBUG")
 
-    async def _start_mcp_server(self):
-        """Start the MCP server."""
+    async def _start_mcp_server(self, args=None):
+        """Start the MCP server using the selected transport."""
         try:
             server = StructMCPServer()
-            await server.run()
+            transport = getattr(args, 'transport', 'stdio') if args else 'stdio'
+            # Map CLI args to server.run kwargs
+            run_kwargs = {
+                "transport": transport,
+                "show_banner": getattr(args, 'show_banner', True) if args else True,
+            }
+            # Determine FastMCP logger level
+            fastmcp_log_level = None
+            if args:
+                fastmcp_log_level = getattr(args, 'fastmcp_log_level', None)
+                if not fastmcp_log_level and getattr(args, 'debug', False):
+                    fastmcp_log_level = 'DEBUG'
+            if fastmcp_log_level:
+                run_kwargs["fastmcp_log_level"] = fastmcp_log_level
+
+            if transport in {"http", "sse"}:
+                # uvicorn expects lowercase levels like "info"/"debug"
+                uvicorn_level = None
+                if args:
+                    uvicorn_level = getattr(args, 'uvicorn_log_level', None)
+                    if not uvicorn_level and getattr(args, 'debug', False):
+                        uvicorn_level = 'debug'
+                    if not uvicorn_level:
+                        # Default to args.log if provided, else None
+                        uvicorn_level = getattr(args, 'log', None)
+                run_kwargs.update({
+                    "host": getattr(args, 'host', None),
+                    "port": getattr(args, 'port', None),
+                    "path": getattr(args, 'path', None),
+                    "log_level": (uvicorn_level.lower() if isinstance(uvicorn_level, str) else uvicorn_level),
+                })
+                if transport == "http":
+                    run_kwargs["stateless_http"] = getattr(args, 'stateless_http', None)
+            await server.run(**run_kwargs)
         except Exception as e:
             self.logger.error(f"Error starting MCP server: {e}")
             raise

struct_module/main.py

@@ -1,5 +1,6 @@
 import argparse
 import logging
+import os
 from dotenv import load_dotenv
 from struct_module.utils import read_config_file, merge_configs
 from struct_module.commands.generate import GenerateCommand
@@ -65,7 +66,16 @@ def main():
       file_config = read_config_file(args.config_file)
       args = argparse.Namespace(**merge_configs(file_config, args))
 
-    logging_level = getattr(logging, getattr(args, 'log', 'INFO').upper(), logging.INFO)
+    # Resolve logging level precedence: STRUCT_LOG_LEVEL env > --debug (if present) > --log
+    env_level = os.getenv('STRUCT_LOG_LEVEL')
+    if env_level:
+        logging_level = getattr(logging, env_level.upper(), logging.INFO)
+    else:
+        # Some commands (like mcp) may add a --debug flag; respect it
+        if getattr(args, 'debug', False):
+            logging_level = logging.DEBUG
+        else:
+            logging_level = getattr(logging, getattr(args, 'log', 'INFO').upper(), logging.INFO)
 
     configure_logging(level=logging_level, log_file=getattr(args, 'log_file', None))