Agents API

The Agents API provides methods to interact with Mastra AI agents, including generating responses, streaming interactions, and managing agent tools.

Initialize Mastra Client


import { MastraClient } from "@mastra/client-js";
 
const client = new MastraClient();

Getting All Agents

Retrieve a list of all available agents:


const agents = await client.getAgents();

Working with a Specific Agent

Get an instance of a specific agent:


const agent = client.getAgent("agent-id");

Agent Methods

Get Agent Details

Retrieve detailed information about an agent:


const details = await agent.details();

Generate Response

Generate a response from the agent:


const response = await agent.generate({
  messages: [
    {
      role: "user",
      content: "Hello, how are you?",
    },
  ],
  threadId: "thread-1", // Optional: Thread ID for conversation context
  resourceid: "resource-1", // Optional: Resource ID
  output: {}, // Optional: Output configuration
});

Stream Response

Stream responses from the agent for real-time interactions:


const response = await agent.stream({
  messages: [
    {
      role: "user",
      content: "Tell me a story",
    },
  ],
});
 
// Process data stream with the processDataStream util
response.processDataStream({
  onTextPart: (text) => {
    process.stdout.write(text);
  },
  onFilePart: (file) => {
    console.log(file);
  },
  onDataPart: (data) => {
    console.log(data);
  },
  onErrorPart: (error) => {
    console.error(error);
  },
});
 
// You can also read from response body directly
const reader = response.body.getReader();
while (true) {
  const { done, value } = await reader.read();
  if (done) break;
  console.log(new TextDecoder().decode(value));
}

Client tools

Client-side tools allow you to execute custom functions on the client side when the agent requests them.

Basic Usage


import { createTool } from '@mastra/core/tools';
import { z } from 'zod';
 
const colorChangeTool = createTool({
  id: 'changeColor',
  description: 'Changes the background color',
  inputSchema: z.object({
    color: z.string(),
  }),
  execute: async ({ context }) => {
    document.body.style.backgroundColor = context.color;
    return { success: true };
  }
})
 
 
// Use with generate
const response = await agent.generate({
  messages: 'Change the background to blue',
  clientTools: {colorChangeTool},
});
 
// Use with stream
const response = await agent.stream({
  messages: 'Change the background to green',
  clientTools: {colorChangeTool},
});
 
response.processDataStream({
  onTextPart: (text) => console.log(text),
  onToolCallPart: (toolCall) => console.log('Tool called:', toolCall.toolName),
});

Get Agent Tool

Retrieve information about a specific tool available to the agent:


const tool = await agent.getTool("tool-id");

Get Agent Evaluations

Get evaluation results for the agent:


// Get CI evaluations
const evals = await agent.evals();
 
// Get live evaluations
const liveEvals = await agent.liveEvals();