fix: Call-out that direct method calls must used keyword arguments

[zastrowm]

Description

Follow-up to strands-agents/tools/issues/194 where examples were not using keyword arguments and thus not working correctly.

Type of Change

• Content update/revision

Motivation and Context

strands-agents/tools#194 revealed that our docs should call out to always use keyword parameters

Areas Affected

Tools overview

Screenshots

N/A

Checklist

• I have read the CONTRIBUTING document
• My changes follow the project's documentation style
• I have tested the documentation locally using mkdocs serve
• Links in the documentation are valid and working
• Images/diagrams are properly sized and formatted
• All new and existing tests pass

Additional Notes

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