Feature Request: tool:pre Event for PreToolUse Validation Hooks

Target: clawdbot/clawdbot
Status: Draft (needs gh auth to submit)
Authors: Monolith + Larry
Date: 2026-01-25

Summary

Add a tool:pre (or tool:before) event that fires before a tool call is executed, allowing hooks to validate, modify, or block the call.

Motivation

Currently Clawdbot has tool_result_persist (post-tool) but no pre-execution hook. This limits the ability to implement:

• Safety guards — Block dangerous commands before execution (e.g., rm -rf /, fork bombs)
• Anti-sycophancy filters — Detect and flag problematic patterns in outbound messages
• Context thresholds — Warn when context usage exceeds limits
• Secrets detection — Prevent accidental credential exposure in commands
• Cross-agent coordination — Validate claims before artifact creation (G10 protocol)

Proposed Event Schema

interface PreToolEvent {
  type: 'tool:pre';
  toolName: string;
  args: Record<string, unknown>;
  sessionKey: string;
  agentId: string;
}

interface PreToolResult {
  action: 'allow' | 'block' | 'modify';
  reason?: string;
  modifiedArgs?: Record<string, unknown>;  // if action === 'modify'
}

Use Cases

1. Dangerous Command Blocking

guards:
  - pattern: 'rm -rf /'
    action: block
    reason: 'Refusing to delete root filesystem'

2. Message Quality Scoring

Before message.send, validate content quality and block low-effort responses.

3. Confirmation Prompts

For destructive operations (git push --force, DROP TABLE), require explicit confirmation.

Prior Art

• Claude Code has PreToolUse hooks
• MCP servers can implement tool validation
• Our prototype: sync/hooks/pre-tool-hook.py in WireParkHackerz/ai-soul-team

Implementation Notes

The event should fire after the LLM returns a tool call but before execution. Hooks should be:

• Async-capable (for external validation)
• Chainable (multiple hooks can run in sequence)
• Fail-safe (hook errors should not block all tool calls)

Related

• Existing events: command:new, agent:bootstrap, gateway:startup, tool_result_persist
• Docs: /docs/tools/index.md

To Submit

gh auth login
gh issue create --repo clawdbot/clawdbot --title "Feature: Add tool:pre event for PreToolUse validation hooks" --body-file sync/docs/pretooluse-feature-request.md