Anthropic SDK Integration

npm install veto-sdk @anthropic-ai/sdk

import Anthropic from '@anthropic-ai/sdk';
import { Veto, ToolCallDeniedError } from 'veto-sdk';
import { toAnthropic, fromAnthropicToolUse } from 'veto-sdk/providers';

const client = new Anthropic({ apiKey: process.env.ANTHROPIC_API_KEY });
const veto = await Veto.init();

const vetoTools = [
  {
    name: 'transfer_funds',
    description: 'Transfer money between bank accounts',
    inputSchema: {
      type: 'object' as const,
      properties: {
        amount: { type: 'number' },
        from_account: { type: 'string' },
        to_account: { type: 'string' },
      },
      required: ['amount', 'from_account', 'to_account'],
    },
  },
];

const anthropicTools = vetoTools.map(toAnthropic);

const response = await client.messages.create({
  model: 'claude-sonnet-4-20250514',
  max_tokens: 1024,
  messages: [{ role: 'user', content: 'Transfer $500 from ACC-1 to ACC-2' }],
  tools: anthropicTools,
});

for (const block of response.content) {
  if (block.type !== 'tool_use') continue;
  const vetoCall = fromAnthropicToolUse(block);

  // Optional preflight check (no execution, no ToolCallDeniedError throw)
  const guard = await veto.guard(vetoCall.name, vetoCall.arguments, {
    sessionId: 'anthropic-session-1',
    agentId: 'anthropic-agent',
  });
  if (guard.decision !== 'allow') {
    console.log(`Blocked at preflight: ${guard.decision} ${guard.reason ?? ''}`);
    continue;
  }

  // Execution-time enforcement
  const wrapped = veto.wrap([{
    name: vetoCall.name,
    handler: async (args: Record<string, unknown>) => ({ ok: true, args }),
  }]);

  try {
    const result = await wrapped[0].handler(vetoCall.arguments);
    console.log(result);
  } catch (error) {
    if (error instanceof ToolCallDeniedError) {
      console.log(`Blocked by policy: ${error.reason}`);
    } else {
      throw error;
    }
  }
}