feat: add message to ProgressNotification

[aksheyd]

Added an optional message field to ProgressNotificationParams according to latest mcp spec.

Motivation and Context

Addressing #399 to add spec guidelines to sdk

How Has This Been Tested?

Added test_progress_notification to test messages bidirectionally. I'm hesitant that covers all angles so I'd like if someone could look over the test case a little more.

Breaking Changes

This did break test_176_progress_token, but it was over a schema check rather than implementation of the code (checking message=None since it's now an optional (default set to None) arg in fastmcp.server.report_progress().

Outside of test cases, no. Since the message field is optional, it shouldn't impact anything on release.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

This is my first pull request to MCP (and honestly, to a codebase of this magnitude and quality). I’m incredibly excited to contribute, but also want to acknowledge that I might have missed some things. I’d really appreciate any extra scrutiny or tips reviewers can offer, especially around the test cases. Thanks in advance, and apologies if anything is off!

[ihrpr]

Thank you for adding the support for the message in Progress Notifications!

Some comments:

• Having the message parameter on the progress() method (not the context manager) would be more intuitive

It would look like

async with progress(total=100) as p:
    await p.progress(10, message="Loading configuration...")
    await p.progress(30, message="Connecting to database...")
    await p.progress(40, message="Fetching data...")
    await p.progress(20, message="Processing results...")

would be great cover ProgressContext with tests as well

[aksheyd]

Thank you!

Absolutely, that makes sense. I reviewed and committed your changes, and I'll add a test case for the ProgressContext as soon as possible. I also have the PR typecheck error fixed and can push that with the new test case.

[aksheyd]

Added a test case for the progress context manager.

Looks like the 3.11 check failed on test_188_concurrency.py by fractions of a second. It passed locally for me, so not sure how to best approach this. Would it make sense to trigger a re-run with a blank commit?

[ihrpr]

thank you!

would be great to remove sleep in tests before merging

[ihrpr]

Thank you!