fix: accept wildcard media types in Accept header per RFC 7231

[shivama205]

Summary

• Fix _check_accept_headers to accept wildcard media types (*/*, application/*, text/*) in the Accept header, per RFC 7231, section 5.3.2
• Strip quality value parameters (e.g. ;q=0.8) before matching media types
• Add comprehensive tests for wildcard acceptance and rejection scenarios

Problem

The server rejected requests with wildcard Accept headers like */* or application/*, returning 406 Not Acceptable. This violated RFC 7231 and broke interoperability with HTTP clients that send Accept: */* by default (e.g. httpx, requests).

Closes#1641

Test plan

• Wildcard */* accepted for both SSE and JSON-only modes
• application/* + text/* accepted for SSE mode
• application/* alone correctly rejected for SSE mode (doesn't cover text/event-stream)
• Quality parameters (*/*;q=0.8) handled correctly
• Truly missing Accept header still rejected
• Incompatible types (text/html) still rejected
• All 1134 existing tests pass
• Linting, formatting, and type checks clean

[shivama205]

Hi @Kludex@maxisbey — could you please review this when you get a chance? This fixes #1641 (wildcard Accept header support per RFC 7231). All CI checks are passing. Thanks!

[shivama205]

@felixweinberger@maxisbey could you please review this when you get a chance? Thanks!

[shivama205]

Bumping this — just rebased onto latest main (clean, no conflicts). This fixes a real interoperability bug: clients like httpx and requests send Accept: */* by default and currently get a 406 Not Acceptable. All CI is passing.

If anyone's on the MCP Discord, would really appreciate a ping to get eyes on this. Happy to make any changes to get it merged. 🙏

[maxisbey]

Thanks for this — the approach is correct and the test coverage is great. Two small asks before merge (suggestions inline, should be one-click applies).

_{AI Disclaimer}

[shivama205]

Thanks for the thorough review @maxisbey! Applied all your suggestions:

• Added .lower() for case-insensitive media type matching per RFC 7231
• Switched from startswith to exact match to prevent over-matching (e.g. application/json-patch+json) — good eye on that one
• Replaced headers.update({"Accept": None}) with headers.pop("Accept") at all three locations, much cleaner