docs: Enhance fetch_user_age tool: include UID and correct output format

[Wania-Kazmi]

Background
The existing fetch_user_age tool only displayed the user’s name and hard-coded age, and the printed comment was misleading. It also neglected the user’s unique identifier.

Issue

• Output string in context.md was inaccurate for given string in function fetch_user_age:

  f"User {wrapper.context.name} is 47 years old"
  # The user John is 47 years old.

• The uid field of UserInfo was never used, reducing context completeness.

Changes

1. Use uid in the tool’s response
   Updated fetch_user_age to reference both name and uid from wrapper.context.

   - return f"User {wrapper.context.name} is 47 years old"
   + return f"User {wrapper.context.name} (ID: {wrapper.context.uid}) is 47 years old"

2. Correct expected output in example
   Adjusted the printed comment in context.md to match the new response format.

   - # The user John is 47 years old.
   + # User John (ID: 123) is 47 years old

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These updates ensure the tool provides a more complete and accurate user context, improving both clarity and correctness.