modelcontextprotocol/python-sdk
Watch
1
0
Fork
You've already forked python-sdk
 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Stop advertising MCP_* env vars for MCPServer settings; drop pydantic-settings (#3170)

Browse source
This commit is contained in:
Max 2026-07-25 23:22:27 +01:00 • committed by GitHub
commit 3212591946
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
1 changed files with 24 additions and 19 deletions
Download patch file Download diff file Expand all files Collapse all files

16
docs/migration.md
View file

@ -684,6 +684,22 @@ app = Starlette(routes=[Mount("/", app=mcp.streamable_http_app(json_response=Tru
If you were mutating these via `mcp.settings` after construction (e.g., `mcp.settings.port = 9000`), pass them to `run()` / `sse_app()` / `streamable_http_app()` instead — these fields no longer exist on `Settings`. The `debug` and `log_level` parameters remain on the constructor.
### `MCP_*` environment variables and `.env` files are no longer read
The `Settings` docstring advertised configuration via `MCP_*` environment variables and a `.env` file (e.g. `MCP_DEBUG=true`), but constructor arguments have always taken precedence, so those environment variables never took effect. `Settings` is now a plain Pydantic model rather than a `pydantic-settings` `BaseSettings`, and `pydantic-settings` is no longer a dependency of the SDK.
If you want environment-driven configuration, read the environment yourself and pass the values to the constructor:
```python
import os
from mcp.server.mcpserver import MCPServer
mcp = MCPServer("Demo", debug=os.environ.get("MCP_DEBUG") == "true")
```
If your own code uses `pydantic-settings`, add it to your project's dependencies directly.
### Streamable HTTP request bodies are limited to 4 MiB
V2 applies a 4 MiB default limit to Streamable HTTP POST bodies and returns HTTP 413 before parsing