claude-code - 💡(How to fix) Fix SessionStart hook fails with agent type: ToolUseContext is required [2 comments, 2 participants]

SessionStart:startup hook error The error message itself acknowledges this is a bug.

TL;DR

Change the hook type or move the agent hook to a compatible event like PreToolUse to resolve the incompatibility issue.

Guidance

• Identify alternative events like PreToolUse or PostToolUse where ToolUseContext is available and agent hooks can be used.
• Consider modifying the .claude/settings.json to use a different hook type that does not require ToolUseContext.
• Verify the compatibility of the chosen hook type with the SessionStart event to avoid similar issues.
• Review the documentation for any updates on using agent hooks with SessionStart or other events.

Example

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "tool-name",
        "hooks": [
          {
            "type": "agent",
            "prompt": "Read project files and summarize status",
            "timeout": 120
          }
        ]
      }
    ]
  }
}

Notes

The current implementation of agent hooks in SessionStart is acknowledged as a bug, and moving to a compatible event is a workaround until the issue is resolved.

Recommendation

Apply workaround: Move the agent hook to a compatible event like PreToolUse to utilize the required ToolUseContext. This change allows the agent hook to execute successfully while waiting for a fix for the SessionStart event compatibility issue.