Move to the MCP Python SDK 2 (1.1.0)

README.md

@@ -312,7 +312,7 @@ agent = Agent(
 Expose the programmatic tools as an MCP server for any MCP-compatible client:
 
 ```python
-from agent_codemode import codemode_server, configure_server
+from agent_codemode import configure_server, run_server
 from agent_codemode import ToolRegistry, MCPServerConfig, CodeModeConfig
 
 # Create and configure registry with MCP servers to compose
@@ -331,7 +331,7 @@ config = CodeModeConfig(
 )
 
 configure_server(config=config, registry=registry)
-codemode_server.run()
+run_server()  # stdio; run_server(transport="streamable-http", host=..., port=...) for HTTP
 ```
 
 Or start with command line:

agent_codemode/__init__.py

@@ -49,6 +49,7 @@
 from .proxy.meta_tools import MetaToolProvider
 from .server import configure as configure_server
 from .server import mcp as codemode_server
+from .server import run as run_server
 from .toolset import PYDANTIC_AI_AVAILABLE, CodemodeToolset
 from .types import (
     CodeModeConfig,
@@ -90,6 +91,7 @@
     "configure_server",
     "parallel",
     "retry",
+    "run_server",
     "run_with_timeout",
     "setup_skills_directory",
     # Helpers (from agent_skills)

agent_codemode/__version__.py

@@ -4,4 +4,4 @@
 
 """Agent Codemode."""
 
-__version__ = "1.0.1"
+__version__ = "1.1.0"

agent_codemode/composition/executor.py

@@ -702,7 +702,10 @@ async def call_tool(tool_name: str, arguments: dict[str, Any]) -> Any:
 
     is_error = False
     if isinstance(result, dict):
-        is_error = result.get("isError", False)
+        is_error = result.get("isError", result.get("is_error", False))
+    elif hasattr(result, "is_error"):
+        # A ``CallToolResult`` of mcp 2, whose fields are snake_case.
+        is_error = result.is_error
     elif hasattr(result, "isError"):
         is_error = result.isError
 

agent_codemode/discovery/codegen.py

@@ -133,7 +133,10 @@ async def call_tool(tool_name: str, arguments: dict[str, Any]) -> Any:
     # Check for error response
     is_error = False
     if isinstance(result, dict):
-        is_error = result.get("isError", False)
+        is_error = result.get("isError", result.get("is_error", False))
+    elif hasattr(result, "is_error"):
+        # A ``CallToolResult`` of mcp 2, whose fields are snake_case.
+        is_error = result.is_error
     elif hasattr(result, "isError"):
         is_error = result.isError
 

agent_codemode/proxy/mcp_client.py

@@ -124,11 +124,14 @@ async def _get_http_session(self):
             return self._http_session
 
         from mcp.client.session import ClientSession
-        from mcp.client.streamable_http import streamablehttp_client
+        from mcp.client.streamable_http import streamable_http_client
 
-        http_ctx = streamablehttp_client(self.url)
+        # mcp 2: the transport yields the two streams only; the session id
+        # callback of mcp 1 is gone, and headers or timeouts would be set on
+        # an ``httpx2.AsyncClient`` passed as ``http_client``.
+        http_ctx = streamable_http_client(self.url)
         self._http_ctx = http_ctx
-        read_stream, write_stream, _get_session_id = await http_ctx.__aenter__()
+        read_stream, write_stream = await http_ctx.__aenter__()
         http_session = ClientSession(read_stream, write_stream)
         self._http_session = http_session
         await http_session.__aenter__()

agent_codemode/server.py

@@ -25,16 +25,16 @@
 
 import anyio
 import mcp.types as types
-from mcp.server.lowlevel import Server
+from mcp.server import Server, ServerRequestContext
 
 from .composition.executor import CodeModeExecutor
 from .discovery.registry import ToolRegistry
 from .types import CodeModeConfig
 
 logger = logging.getLogger(__name__)
 
-# Create the MCP server
-mcp = Server("codemode")
+# The MCP server is built at the end of this module, once its handlers
+# exist: mcp 2's lowlevel ``Server`` takes them as constructor arguments.
 
 # Global instances (configured at startup)
 _registry: Optional[ToolRegistry] = None
@@ -119,7 +119,7 @@ def _build_tools() -> list[types.Tool]:
             types.Tool(
                 name=name,
                 description=description,
-                inputSchema=parameters,
+                input_schema=parameters,
             )
         )
 
@@ -129,7 +129,7 @@ def _build_tools() -> list[types.Tool]:
             types.Tool(
                 name="save_skill",
                 description="Save a reusable skill (code-based tool composition).",
-                inputSchema={
+                input_schema={
                     "type": "object",
                     "required": ["name", "code", "description"],
                     "properties": {
@@ -144,7 +144,7 @@ def _build_tools() -> list[types.Tool]:
             types.Tool(
                 name="run_skill",
                 description="Execute a saved skill.",
-                inputSchema={
+                input_schema={
                     "type": "object",
                     "required": ["name"],
                     "properties": {
@@ -156,7 +156,7 @@ def _build_tools() -> list[types.Tool]:
             types.Tool(
                 name="list_skills",
                 description="List available skills.",
-                inputSchema={
+                input_schema={
                     "type": "object",
                     "properties": {
                         "tags": {"type": "array", "items": {"type": "string"}},
@@ -166,7 +166,7 @@ def _build_tools() -> list[types.Tool]:
             types.Tool(
                 name="delete_skill",
                 description="Delete a saved skill.",
-                inputSchema={
+                input_schema={
                     "type": "object",
                     "required": ["name"],
                     "properties": {
@@ -177,7 +177,7 @@ def _build_tools() -> list[types.Tool]:
             types.Tool(
                 name="get_execution_history",
                 description="Get recent tool execution history.",
-                inputSchema={
+                input_schema={
                     "type": "object",
                     "properties": {
                         "limit": {"type": "integer", "default": 10},
@@ -187,7 +187,7 @@ def _build_tools() -> list[types.Tool]:
             types.Tool(
                 name="add_mcp_server",
                 description="Add a new MCP server to discover tools from.",
-                inputSchema={
+                input_schema={
                     "type": "object",
                     "required": ["name"],
                     "properties": {
@@ -588,25 +588,47 @@ async def handle_add_mcp_server(arguments: dict[str, Any]) -> dict[str, Any]:
 # =============================================================================
 
 
-@mcp.list_tools()
-async def list_tools() -> list[types.Tool]:
+async def list_tools(
+    ctx: ServerRequestContext, params: types.PaginatedRequestParams | None
+) -> types.ListToolsResult:
     """Return the list of available tools."""
     config = _config or CodeModeConfig()
     if config.allow_direct_tool_calls:
-        return TOOLS
-    return [tool for tool in TOOLS if tool.name != "call_tool"]
+        return types.ListToolsResult(tools=TOOLS)
+    return types.ListToolsResult(tools=[tool for tool in TOOLS if tool.name != "call_tool"])
+
 
+async def call_tool(
+    ctx: ServerRequestContext, params: types.CallToolRequestParams
+) -> types.CallToolResult:
+    """Handle tool calls.
 
-@mcp.call_tool()
-async def call_tool(name: str, arguments: dict[str, Any]) -> list[types.TextContent]:
-    """Handle tool calls."""
-    handler = TOOL_HANDLERS.get(name)
+    A failure is answered as a result with ``is_error`` set, the way mcp 1's
+    decorator did it: mcp 2's lowlevel server turns an exception raised here
+    into a JSON-RPC error instead, which an agent cannot read as a tool
+    outcome.
+    """
+    handler = TOOL_HANDLERS.get(params.name)
     if handler is None:
-        raise ValueError(f"Unknown tool: {name}")
+        return types.CallToolResult(
+            content=[types.TextContent(type="text", text=f"Unknown tool: {params.name}")],
+            is_error=True,
+        )
 
-    result = await handler(arguments)
+    try:
+        result = await handler(params.arguments or {})
+    except Exception as e:  # every failure is reported to the agent
+        logger.debug("Tool %s failed", params.name, exc_info=e)
+        return types.CallToolResult(
+            content=[types.TextContent(type="text", text=str(e))],
+            is_error=True,
+        )
     json_str = json.dumps(result, indent=2)
-    return [types.TextContent(type="text", text=json_str)]
+    return types.CallToolResult(content=[types.TextContent(type="text", text=json_str)])
+
+
+# Create the MCP server
+mcp = Server("codemode", on_list_tools=list_tools, on_call_tool=call_tool)
 
 
 # =============================================================================
@@ -629,26 +651,15 @@ def run(transport: str = "stdio", host: str = "127.0.0.1", port: int = 8000) ->
 
     if transport == "streamable-http":
         import uvicorn
-        from mcp.server.streamable_http import StreamableHTTPServerTransport
-        from starlette.applications import Starlette
-        from starlette.routing import Route
 
-        async def handle_mcp(request):
-            transport_ctx: Any = StreamableHTTPServerTransport(
-                "/mcp", request.scope, request.receive, request._send
-            )
-            async with transport_ctx as transport:
-                await mcp.run(
-                    transport.read_stream,
-                    transport.write_stream,
-                    mcp.create_initialization_options(),
-                )
-
-        starlette_app = Starlette(
-            debug=True,
-            routes=[
-                Route("/mcp", endpoint=handle_mcp, methods=["POST"]),
-            ],
+        # Stateless, as before: each request is served on a transport of its
+        # own. ``host`` is passed on because the SDK enables DNS-rebinding
+        # protection, with a localhost-only allowlist, when it is a loopback
+        # address — a server bound elsewhere must not inherit that list.
+        starlette_app = mcp.streamable_http_app(
+            streamable_http_path="/mcp",
+            stateless_http=True,
+            host=host,
         )
 
         uvicorn.run(starlette_app, host=host, port=port)

docs/docs/index.mdx

@@ -247,11 +247,11 @@ See [Integrations](./integrations/index.mdx) for complete documentation.
 
 **Exposed as an MCP Server:**
 ```python
-from agent_codemode import codemode_server, configure_server
+from agent_codemode import configure_server, run_server
 
 # Configure with your registry
 configure_server(config=config, registry=registry)
-codemode_server.run()
+run_server()
 ```
 
 Or run directly:

docs/docs/integrations/index.mdx

@@ -136,13 +136,13 @@ python -m agent_codemode.server
 Or programmatically:
 
 ```python
-from agent_codemode import codemode_server, configure_server, ToolRegistry, MCPServerConfig
+from agent_codemode import configure_server, run_server, ToolRegistry, MCPServerConfig
 
 registry = ToolRegistry()
 registry.add_server(MCPServerConfig(name="filesystem", command="npx", args=["@anthropic-ai/mcp-server-filesystem"]))
 
 configure_server(registry=registry)
-codemode_server.run()
+run_server()
 ```
 
 The server exposes tools for:

docs/docs/skills/index.mdx

@@ -353,16 +353,15 @@ When running Agent Codemode as an MCP server, skills are exposed through dedicat
 - **`run_skill`**: Execute a saved skill by name
 
 ```python
-from agent_codemode import codemode_server, configure_server
-from agent_codemode import CodeModeConfig
+from agent_codemode import CodeModeConfig, configure_server, run_server
 
 config = CodeModeConfig(
     skills_path="./skills",
     # ... other config
 )
 
 configure_server(config=config)
-codemode_server.run()
+run_server()
 ```
 
 ## Pydantic AI Integration

docs/docusaurus.config.js

@@ -161,7 +161,7 @@ module.exports = {
             },
             {
               label: 'Bluesky',
-              href: 'https://assets.datalayer.tech/logos-social-grey/youtube.svg',
+              href: 'https://assets.datalayer.tech/logos-social-grey/bluesky.svg',
             },
             {
               label: 'LinkedIn',

examples/patterns/codemode_example.py

@@ -158,8 +158,9 @@ async def _server():
     # Configure with MCP servers
     configure_server()
 
-    # Run the MCP server (uses FastMCP under the hood)
-    codemode_server.run()
+    # Serve it over stdio (the MCP SDK's lowlevel Server under the hood)
+    from agent_codemode.server import run
+    run()
 
 Or from the command line:
 

examples/simple/example_mcp_server.py

@@ -13,10 +13,10 @@
 from pathlib import Path
 from typing import Optional
 
-from mcp.server.fastmcp import FastMCP
+from mcp.server import MCPServer
 from typing_extensions import TypedDict
 
-mcp = FastMCP("example-mcp-server")
+mcp = MCPServer("example-mcp-server")
 
 # Base directory for file operations - defaults to /tmp if CWD is not writable
 _BASE_DIR: Path | None = None

examples/skills/example_mcp_server.py

@@ -13,10 +13,10 @@
 from pathlib import Path
 from typing import Optional
 
-from mcp.server.fastmcp import FastMCP
+from mcp.server import MCPServer
 from typing_extensions import TypedDict
 
-mcp = FastMCP("example-mcp-server")
+mcp = MCPServer("example-mcp-server")
 
 # Base directory for file operations - defaults to /tmp if CWD is not writable
 _BASE_DIR: Path | None = None

pyproject.toml

@@ -23,7 +23,10 @@ classifiers = [
 dependencies = [
     "agent-skills",
     "code-sandboxes",
-    "mcp[cli]>=1.10.1,<2",
+    # The MCP Python SDK 2: FastMCP became MCPServer, the lowlevel Server takes
+    # its handlers as constructor arguments, and clients come with httpx2. See
+    # https://py.sdk.modelcontextprotocol.io/v2/migration/
+    "mcp[cli]>=2,<3",
     "pydantic>=2.0",
     "httpx>=0.24",
 ]

tests/conftest.py

@@ -9,28 +9,6 @@
 import pytest
 
 
-def _rebuild_fastmcp_settings() -> None:
-    """Resolve the forward reference in FastMCP's ``Settings`` model.
-
-    ``mcp.server.fastmcp.server.Settings.lifespan`` is annotated with
-    ``FastMCP``, which is defined further down the same module, and upstream
-    never calls ``model_rebuild()``. Recent pydantic-settings releases warn
-    (``IncompleteFieldDefinitionWarning``) when such a model is instantiated,
-    and this suite turns warnings into errors, so collection fails as soon as
-    anything constructs a FastMCP server. Rebuilding the model once resolves
-    the reference for real instead of muting the warning.
-    """
-    try:
-        from mcp.server.fastmcp.server import Settings
-    except ImportError:  # pragma: no cover - mcp layout changed
-        return
-    if not getattr(Settings, "__pydantic_complete__", True):
-        Settings.model_rebuild()
-
-
-_rebuild_fastmcp_settings()
-
-
 @pytest.fixture
 def skills_dir(tmp_path: Path) -> Path:
     """Create a temporary skills directory."""