feat: Add tool annotations for improved LLM tool understanding

[bryankthompson]

Summary

Adds MCP tool annotations (readOnlyHint, destructiveHint, title) to all 7 tools to help LLMs better understand tool behavior and make safer decisions about tool execution.

Changes

• Added readOnlyHint: true to read-only tools:

  • excel_read_sheet - Read Excel Sheet
  • excel_describe_sheets - Describe Excel Sheets
  • excel_screen_capture - Capture Excel Screenshot

• Added destructiveHint: true to tools that modify data:

  • excel_write_to_sheet - Write to Excel Sheet
  • excel_copy_sheet - Copy Excel Sheet
  • excel_create_table - Create Excel Table
  • excel_format_range - Format Excel Range

• Added title annotations for human-readable display

Why This Matters

• Annotations provide semantic metadata that helps MCP clients understand tool behavior
• Clients like Claude Code can auto-approve tools with readOnlyHint: true without user confirmation
• Destructive tools trigger confirmation prompts, adding safety guardrails
• Enables better UI/UX with appropriate warnings/icons based on tool characteristics

Testing

• Project builds successfully (go build ./...)
• No test failures
• Annotations use standard mcp-go convenience functions (WithTitleAnnotation, WithReadOnlyHintAnnotation, WithDestructiveHintAnnotation)

Before/After

Before:

server.AddTool(mcp.NewTool("excel_read_sheet",
    mcp.WithDescription("Read values from Excel sheet..."),
    ...
), handler)

After:

server.AddTool(mcp.NewTool("excel_read_sheet",
    mcp.WithDescription("Read values from Excel sheet..."),
    mcp.WithTitleAnnotation("Read Excel Sheet"),
    mcp.WithReadOnlyHintAnnotation(true),
    ...
), handler)

🤖 Generated with Claude Code