feat: Add tool annotations for improved LLM tool understanding

[bryankthompson]

Summary

Adds MCP tool annotations (readOnlyHint, destructiveHint, title) to all 13 tools to help LLMs better understand tool behavior and make safer decisions about tool execution.

Changes

• Added ToolAnnotations type import to ToolSchema
• Added readOnlyHint: true to read-only tools:
  • wait - Only pauses execution, no browser state changes
  • snapshot - Captures current page state without modification
  • getConsoleLogs - Reads existing console logs
  • screenshot - Captures image of current page state
• Added destructiveHint: true to tools that interact with/modify the browser:
  • navigate - Changes current URL
  • goBack / goForward - Modifies browser history position
  • pressKey - Simulates keyboard input
  • click - Triggers element interactions
  • drag - Moves elements
  • hover - Can trigger hover events
  • type - Enters text into elements
  • selectOption - Changes form selection state
• Added title annotations for human-readable display
• Updated server.ts to include annotations in tools/list response

Why This Matters

• Annotations provide semantic metadata that helps LLMs understand tool behavior
• LLMs can make better decisions about when to use tools and in what order
• readOnlyHint indicates tools safe to call without side effects
• destructiveHint signals tools that modify browser state, requiring more careful consideration
• Enables safer tool execution by distinguishing observation from action tools

Testing

• TypeScript types verified against @modelcontextprotocol/sdk v1.25.1
• Annotation values correctly categorize read-only vs destructive operations
• Note: Full build requires monorepo setup (workspace dependencies)

Before/After Example

Before:

{
  name: "browser_snapshot",
  description: "Take a screenshot of the current browser state"
  // No semantic metadata
}

After:

{
  name: "browser_snapshot",
  description: "Take a screenshot of the current browser state",
  annotations: {
    title: "Snapshot",
    readOnlyHint: true
  }
}

[bryankthompson]

Friendly ping! 👋 Just checking if this PR is still on your radar. Happy to address any feedback or make adjustments if needed. No rush - just wanted to make sure it didn't slip through the cracks.