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Documentation Index

Fetch the complete documentation index at: https://code.claude.com/docs/llms.txt

Use this file to discover all available pages before exploring further.

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Overview

The Claude Agent SDK supports two distinct input modes for interacting with agents:
  • Streaming Input Mode (Default & Recommended) - A persistent, interactive session
  • Single Message Input - One-shot queries that use session state and resuming
This guide explains the differences, benefits, and use cases for each mode to help you choose the right approach for your application. Streaming input mode is the preferred way to use the Claude Agent SDK. It provides full access to the agent’s capabilities and enables rich, interactive experiences. It allows the agent to operate as a long lived process that takes in user input, handles interruptions, surfaces permission requests, and handles session management.

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How It Works

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Benefits

Image Uploads

Attach images directly to messages for visual analysis and understanding

Queued Messages

Send multiple messages that process sequentially, with ability to interrupt

Tool Integration

Full access to all tools and custom MCP servers during the session

Hooks Support

Use lifecycle hooks to customize behavior at various points

Real-time Feedback

See responses as they’re generated, not just final results

Context Persistence

Maintain conversation context across multiple turns naturally

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Implementation Example

import { query, type SDKUserMessage } from "@anthropic-ai/claude-agent-sdk";
import { readFile } from "fs/promises";

async function* generateMessages(): AsyncGenerator<SDKUserMessage> {
  // First message
  yield {
    type: "user",
    message: {
      role: "user",
      content: "Analyze this codebase for security issues"
    },
    parent_tool_use_id: null
  };

  // Wait for conditions or user input
  await new Promise((resolve) => setTimeout(resolve, 2000));

  // Follow-up with image
  yield {
    type: "user",
    message: {
      role: "user",
      content: [
        {
          type: "text",
          text: "Review this architecture diagram"
        },
        {
          type: "image",
          source: {
            type: "base64",
            media_type: "image/png",
            data: await readFile("diagram.png", "base64")
          }
        }
      ]
    },
    parent_tool_use_id: null
  };
}

// Process streaming responses
for await (const message of query({
  prompt: generateMessages(),
  options: {
    maxTurns: 10,
    allowedTools: ["Read", "Grep"]
  }
})) {
  if (message.type === "result" && message.subtype === "success") {
    console.log(message.result);
  }
}

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Single Message Input

Single message input is simpler but more limited.

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When to Use Single Message Input

Use single message input when:
  • You need a one-shot response
  • You do not need image attachments, hooks, etc.
  • You need to operate in a stateless environment, such as a lambda function

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Limitations

Single message input mode does not support:
  • Direct image attachments in messages
  • Dynamic message queueing
  • Real-time interruption
  • Hook integration
  • Natural multi-turn conversations

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Implementation Example

import { query } from "@anthropic-ai/claude-agent-sdk";

// Simple one-shot query
for await (const message of query({
  prompt: "Explain the authentication flow",
  options: {
    maxTurns: 1,
    allowedTools: ["Read", "Grep"]
  }
})) {
  if (message.type === "result" && message.subtype === "success") {
    console.log(message.result);
  }
}

// Continue conversation with session management
for await (const message of query({
  prompt: "Now explain the authorization process",
  options: {
    continue: true,
    maxTurns: 1
  }
})) {
  if (message.type === "result" && message.subtype === "success") {
    console.log(message.result);
  }
}