find_context_parameter treats a Context return annotation as a parameter

Initial checks

• I tested the current main branch (6e30452).
• I searched existing issues and pull requests for this behavior.

Description

find_context_parameter() iterates over every entry returned by typing.get_type_hints(). That mapping includes the function return annotation under the special key "return", even though it is not a parameter.

As a result, a tool, prompt, or resource function whose return annotation is Context (or a union containing Context) is incorrectly recorded as having a context parameter named "return". The SDK later attempts to inject context as a keyword argument with that name, which can produce an unexpected-keyword error when the callable is invoked.

Expected: context detection only examines actual function parameters and ignores the return annotation.

Example code

from mcp.server.mcpserver import Context
from mcp.server.mcpserver.utilities.context_injection import find_context_parameter

def fn(value: int) -> Context:
    ...

print(find_context_parameter(fn))  # current: "return"; expected: None

Environment

• Python 3.12
• MCP Python SDK main at 6e30452

I used AI assistance while investigating this issue and reviewed and reproduced the behavior locally.

Bắt đầu trong mcp/server/mcpserver/utilities/context_injection.py tại find_context_parameter() và tái hiện ví dụ với chú thích kiểu trả về Context. Xác nhận rằng việc phát hiện chỉ kiểm tra các tham số thực tế, bỏ qua chú thích "return" và không còn báo cáo "return" là tham số ngữ cảnh.