feat(mcp_service): enhance MCP server handling to support custom MCP servers

src/services/agent_builder.py

@@ -96,7 +96,7 @@ class AgentBuilder:
         # Get MCP tools from the configuration
         mcp_tools = []
         mcp_exit_stack = None
-        if agent.config.get("mcp_servers"):
+        if agent.config.get("mcp_servers") or agent.config.get("custom_mcp_servers"):
             mcp_tools, mcp_exit_stack = await self.mcp_service.build_tools(
                 agent.config, self.db
             )

src/services/mcp_service.py

@@ -47,6 +47,7 @@ class MCPService:
             tools, exit_stack = await MCPToolset.from_server(
                 connection_params=connection_params
             )
+
             return tools, exit_stack
 
         except Exception as e:
@@ -93,8 +94,10 @@ class MCPService:
         self.exit_stack = AsyncExitStack()
 
         try:
+            mcp_servers = mcp_config.get("mcp_servers", [])
+            if mcp_servers is not None:
                 # Process each MCP server in the configuration
-            for server in mcp_config.get("mcp_servers", []):
+                for server in mcp_servers:
                     try:
                         # Search for the MCP server in the database
                         mcp_server = get_mcp_server(db, server["id"])
@@ -106,12 +109,16 @@ class MCPService:
                         server_config = mcp_server.config_json.copy()
 
                         # Replaces the environment variables in the config_json
-                    if "env" in server_config:
+                        if "env" in server_config and server_config["env"] is not None:
                             for key, value in server_config["env"].items():
-                            if value.startswith("env@@"):
+                                if value and value.startswith("env@@"):
                                     env_key = value.replace("env@@", "")
-                                if env_key in server.get("envs", {}):
+                                    if server.get("envs") and env_key in server.get(
-                                    server_config["env"][key] = server["envs"][env_key]
+                                        "envs", {}
+                                    ):
+                                        server_config["env"][key] = server["envs"][
+                                            env_key
+                                        ]
                                     else:
                                         logger.warning(
                                             f"Environment variable '{env_key}' not provided for the MCP server {mcp_server.name}"
@@ -119,7 +126,9 @@ class MCPService:
                                         continue
 
                         logger.info(f"Connecting to MCP server: {mcp_server.name}")
-                    tools, exit_stack = await self._connect_to_mcp_server(server_config)
+                        tools, exit_stack = await self._connect_to_mcp_server(
+                            server_config
+                        )
 
                         if tools and exit_stack:
                             # Filters incompatible tools
@@ -127,6 +136,7 @@ class MCPService:
 
                             # Filters tools compatible with the agent
                             agent_tools = server.get("tools", [])
+                            if agent_tools:
                                 filtered_tools = self._filter_tools_by_agent(
                                     filtered_tools, agent_tools
                                 )
@@ -143,20 +153,46 @@ class MCPService:
                             )
 
                     except Exception as e:
-                    logger.error(f"Error connecting to MCP server {server['id']}: {e}")
+                        logger.error(
+                            f"Error connecting to MCP server {server.get('id', 'unknown')}: {e}"
+                        )
                         continue
 
+            custom_mcp_servers = mcp_config.get("custom_mcp_servers", [])
+            if custom_mcp_servers is not None:
                 # Process custom MCP servers
-            for server in mcp_config.get("custom_mcp_servers", []):
+                for server in custom_mcp_servers:
+                    if not server:
+                        logger.warning(
+                            "Empty server configuration found in custom_mcp_servers"
+                        )
+                        continue
+
                     try:
+                        logger.info(
+                            f"Connecting to custom MCP server: {server.get('url', 'unknown')}"
+                        )
                         tools, exit_stack = await self._connect_to_mcp_server(server)
+
+                        if tools:
                             self.tools.extend(tools)
+                        else:
+                            logger.warning("No tools returned from custom MCP server")
+                            continue
+
+                        if exit_stack:
                             await self.exit_stack.enter_async_context(exit_stack)
                             logger.info(
                                 f"Custom MCP server connected successfully. Added {len(tools)} tools."
                             )
+                        else:
+                            logger.warning(
+                                "No exit_stack returned from custom MCP server"
+                            )
                     except Exception as e:
-                    logger.error(f"Error connecting to MCP server {server['id']}: {e}")
+                        logger.error(
+                            f"Error connecting to custom MCP server {server.get('url', 'unknown')}: {e}"
+                        )
                         continue
 
             logger.info(