Claude Code / Anthropic SDK

npm install @sigilcore/agent-hooks

import { checkAnthropicToolUse } from '@sigilcore/agent-hooks';

const config = {
  apiKey: process.env.SIGIL_API_KEY!,
  agentId: 'my-claude-agent',
};

// In your PreToolUse hook:
const rejection = await checkAnthropicToolUse(toolUseBlock, config);
if (rejection) {
  // Feed rejection back to Claude as a tool_result error
  return rejection;
}
// Otherwise, let the tool execute normally

{
  action: 'bash',                    // mapped from tool name
  command: block.input['command'],   // bash only
  url: block.input['url'],           // web_fetch only
  path: block.input['path'],         // file_write only
  metadata: block.input,             // full input for custom rules
}

{
  type: 'tool_result',
  tool_use_id: block.id,
  content: JSON.stringify({
    sigil_decision: 'DENIED',
    sigil_error_code: 'SIGIL_POLICY_VIOLATION_BLOCKED_COMMAND',
    sigil_message: 'Command contains blocked string: rm -rf',
    sigil_action_taken: 'halted',
    sigil_next_steps: 'Do not attempt to reframe or retry this action.',
  }),
  is_error: true,
}