Building AI Agents with Claude API

Claude API enables building sophisticated AI agents for autonomous task execution.

Basic Agent Structure

import Anthropic from '@anthropic-ai/sdk';

const client = new Anthropic();

async function runAgent(prompt: string) {
  const message = await client.messages.create({
    model: 'claude-sonnet-4-20250514',
    max_tokens: 4096,
    messages: [{ role: 'user', content: prompt }],
    tools: [
      {
        name: 'search',
        description: 'Search the web for information',
        input_schema: {
          type: 'object',
          properties: {
            query: { type: 'string' },
          },
        },
      },
    ],
  });
  
  return message;
}

Tool Use

async function handleToolUse(content: any) {
  if (content.type === 'tool_use') {
    switch (content.name) {
      case 'search':
        return await search(content.input.query);
      case 'calculate':
        return await calculate(content.input);
      default:
        return 'Unknown tool';
    }
  }
}

Agentic Loop

async function agenticLoop(prompt: string, maxIterations = 10) {
  let messages = [{ role: 'user', content: prompt }];
  
  for (let i = 0; i < maxIterations; i++) {
    const response = await client.messages.create({
      model: 'claude-sonnet-4-20250514',
      max_tokens: 4096,
      messages,
      tools: [...],
    });
    
    // Check if agent is done
    if (response.stop_reason === 'end_turn') {
      return response.content;
    }
    
    // Handle tool calls
    const toolResults = await Promise.all(
      response.content
        .filter(c => c.type === 'tool_use')
        .map(handleToolUse)
    );
    
    messages.push(
      { role: 'assistant', content: response.content },
      { role: 'user', content: toolResults }
    );
  }
}

Conclusion

Claude API provides powerful capabilities for building autonomous AI agents that can reason and use tools.