feat(tools): add mcp support

nanobot/config/schema.py

@@ -1,7 +1,7 @@
 """Configuration schema using Pydantic."""
 
 from pathlib import Path
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, Field, ConfigDict
 from pydantic_settings import BaseSettings
 
 
@@ -213,11 +213,20 @@ class ExecToolConfig(BaseModel):
     timeout: int = 60
 
 
+class MCPServerConfig(BaseModel):
+    """MCP server connection configuration (stdio or HTTP)."""
+    command: str = ""  # Stdio: command to run (e.g. "npx")
+    args: list[str] = Field(default_factory=list)  # Stdio: command arguments
+    env: dict[str, str] = Field(default_factory=dict)  # Stdio: extra env vars
+    url: str = ""  # HTTP: streamable HTTP endpoint URL
+
+
 class ToolsConfig(BaseModel):
     """Tools configuration."""
     web: WebToolsConfig = Field(default_factory=WebToolsConfig)
     exec: ExecToolConfig = Field(default_factory=ExecToolConfig)
     restrict_to_workspace: bool = False  # If true, restrict all tool access to workspace directory
+    mcp_servers: dict[str, MCPServerConfig] = Field(default_factory=dict)
 
 
 class Config(BaseSettings):
@@ -281,6 +290,7 @@ class Config(BaseSettings):
                 return spec.default_api_base
         return None
     
-    class Config:
-        env_prefix = "NANOBOT_"
-        env_nested_delimiter = "__"
+    model_config = ConfigDict(
+        env_prefix="NANOBOT_",
+        env_nested_delimiter="__"
+    )