Replace fastapi_mcp with the MCP Python SDK (FastMCP) to fix RecursionError on recursive Pydantic models, expose explicit @mcp.tool() handlers that call FeatureStore directly, and add registry discovery, data access, and materialization tools with flat LLM-friendly schemas.

Signed-off-by: Chaitany patel <patelchaitany93@gmail.com>

Author: patelchaitany

sdk/python/feast/feature_server.py

@@ -38,6 +38,7 @@
 )
 from fastapi.concurrency import run_in_threadpool
 from fastapi.logger import logger
+from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import JSONResponse
 from fastapi.staticfiles import StaticFiles
 from google.protobuf.json_format import MessageToDict
@@ -353,8 +354,14 @@ async def lifespan(app: FastAPI):
 
         await store.initialize()
         async_refresh()
+
+        mcp_sm = getattr(app.state, "mcp_session_manager", None)
         try:
-            yield
+            if mcp_sm:
+                async with mcp_sm.run():
+                    yield
+            else:
+                yield
         finally:
             stop_refresh()
             if offline_batcher is not None:
@@ -363,6 +370,15 @@ async def lifespan(app: FastAPI):
 
     app = FastAPI(lifespan=lifespan)
 
+    app.add_middleware(
+        CORSMiddleware,
+        allow_origins=["*"],
+        allow_credentials=True,
+        allow_methods=["*"],
+        allow_headers=["*"],
+        expose_headers=["Mcp-Session-Id"],
+    )
+
     @app.post(
         "/get-online-features",
         dependencies=[Depends(inject_user_details)],

sdk/python/feast/infra/mcp_servers/__init__.py

@@ -1,9 +1,10 @@
 # MCP (Model Context Protocol) server implementations for Feast
 
 from .mcp_config import McpFeatureServerConfig
-from .mcp_server import add_mcp_support_to_app
+from .mcp_server import add_mcp_support_to_app, create_mcp_server
 
 __all__ = [
     "McpFeatureServerConfig",
     "add_mcp_support_to_app",
+    "create_mcp_server",
 ]

sdk/python/feast/infra/mcp_servers/mcp_config.py

@@ -8,19 +8,16 @@
 class McpFeatureServerConfig(BaseFeatureServerConfig):
     """MCP (Model Context Protocol) Feature Server configuration."""
 
-    # Feature server type selector
     type: Literal["mcp"] = "mcp"
 
-    # Enable MCP server support - defaults to False as requested
     mcp_enabled: StrictBool = False
 
-    # MCP server name for identification
     mcp_server_name: StrictStr = "feast-mcp-server"
 
-    # MCP server version
     mcp_server_version: StrictStr = "1.0.0"
 
     mcp_transport: Literal["sse", "http"] = "sse"
 
-    # The endpoint definition for transformation_service (inherited from base)
+    mcp_base_path: StrictStr = "/mcp"
+
     transformation_service_endpoint: StrictStr = "localhost:6566"