feat(server): restore dependencies parameter on MCPServer

Restores the `dependencies` parameter that was removed in #1877. The
parameter is read by the `mcp dev` and `mcp install` CLI commands to
auto-populate `uv run --with <pkg>` flags.

Removal without a working replacement breaks high-profile consumers
(awslabs/mcp uses it in 47 servers, mindsdb, redis/mcp-redis). While
PEP 723 inline script metadata is the intended replacement, the CLI
doesn't currently parse it — `uv` only reads PEP 723 when the script
is the direct target, not when wrapped in `mcp run <file>`.

Long-term design (deprecate vs. keep vs. config file) is tracked in
the linked issue.

Github-Issue:#2354

Author: maxisbey

src/mcp/server/mcpserver/server.py

@@ -6,7 +6,7 @@
 import inspect
 import json
 import re
-from collections.abc import AsyncIterator, Awaitable, Callable, Iterable, Sequence
+from collections.abc import AsyncIterator, Awaitable, Callable, Collection, Iterable, Sequence
 from contextlib import AbstractAsyncContextManager, asynccontextmanager
 from typing import Any, Generic, Literal, TypeVar, overload
 
@@ -105,6 +105,9 @@ class Settings(BaseSettings, Generic[LifespanResultT]):
     # prompt settings
     warn_on_duplicate_prompts: bool
 
+    dependencies: list[str]
+    """List of dependencies to install in the server environment. Used by the `mcp install` and `mcp dev` CLI."""
+
     lifespan: Callable[[MCPServer[LifespanResultT]], AbstractAsyncContextManager[LifespanResultT]] | None
     """An async context manager that will be called when the server is started."""
 
@@ -142,6 +145,7 @@ def __init__(
         warn_on_duplicate_resources: bool = True,
         warn_on_duplicate_tools: bool = True,
         warn_on_duplicate_prompts: bool = True,
+        dependencies: Collection[str] = (),
         lifespan: Callable[[MCPServer[LifespanResultT]], AbstractAsyncContextManager[LifespanResultT]] | None = None,
         auth: AuthSettings | None = None,
     ):
@@ -151,9 +155,11 @@ def __init__(
             warn_on_duplicate_resources=warn_on_duplicate_resources,
             warn_on_duplicate_tools=warn_on_duplicate_tools,
             warn_on_duplicate_prompts=warn_on_duplicate_prompts,
+            dependencies=list(dependencies),
             lifespan=lifespan,
             auth=auth,
         )
+        self.dependencies = self.settings.dependencies
 
         self._tool_manager = ToolManager(tools=tools, warn_on_duplicate_tools=self.settings.warn_on_duplicate_tools)
         self._resource_manager = ResourceManager(warn_on_duplicate_resources=self.settings.warn_on_duplicate_resources)

tests/server/mcpserver/test_server.py

@@ -65,6 +65,15 @@ async def test_create_server(self):
         assert len(mcp.icons) == 1
         assert mcp.icons[0].src == "https://example.com/icon.png"
 
+    def test_dependencies(self):
+        """Dependencies list is read by `mcp install` / `mcp dev` CLI commands."""
+        mcp = MCPServer("test", dependencies=["pandas", "numpy"])
+        assert mcp.dependencies == ["pandas", "numpy"]
+        assert mcp.settings.dependencies == ["pandas", "numpy"]
+
+        mcp_no_deps = MCPServer("test")
+        assert mcp_no_deps.dependencies == []
+
     async def test_sse_app_returns_starlette_app(self):
         """Test that sse_app returns a Starlette application with correct routes."""
         mcp = MCPServer("test")