Claude Agent SDK

In this guide, you’ll build an agent that researches the latest TypeScript release and reports what it found, its sources, and the tool cost.

Add to an existing agent

import { agentmuxer } from "@agentmuxer/sdk/claude-agent";

const options = {
  mcpServers: { agentmuxer: agentmuxer() },
  allowedTools: ["mcp__agentmuxer__*"],
};

allowedTools lets Claude call AgentMuxer tools without a separate Claude permission prompt.

Before you start

Node.js 22.18 or later with ESM; see compatibility. Your host must also support the Claude Agent SDK process requirements.
An AgentMuxer application key and credits for paid calls.
An Anthropic API key for the model.

This example asks the agent to spend up to $0.10 on one tool call. Model charges are separate. Set an application spending limit if you need a hard cap; the prompt alone doesn’t enforce one.This example cannot collect payment confirmation. Configure your account for unattended purchases before running it. This setting also affects your personal agents.

Install

In a new directory, create an ESM project and install the integration:

mkdir my-agent
cd my-agent
npm init -y
npm pkg set type=module
npm install @agentmuxer/sdk @anthropic-ai/claude-agent-sdk

Set your keys

Set both keys in your terminal:

export AGENTMUXER_API_KEY='your-application-key'
export ANTHROPIC_API_KEY='your-model-provider-key'

No browser sign-in is needed. Keep both keys on your server and out of source control.

Run Claude with AgentMuxer

Save this as agent.ts. The highlighted lines connect AgentMuxer and let Claude use its tools:

agent.ts

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

const prompt = `Use AgentMuxer to research the latest TypeScript release.
Summarize three changes with sources and report the tool cost.
Spend at most $0.10 on one tool call. Stop if it costs more.`;

for await (const message of query({
  prompt,
  options: {
    mcpServers: { agentmuxer: agentmuxer() },
    allowedTools: ["mcp__agentmuxer__*"],
  },
})) {
  if (message.type !== "result") continue;
  if (message.subtype !== "success") {
    throw new Error(message.errors.join("\n") || message.subtype);
  }
  if (message.is_error) {
    throw new Error(message.result);
  }
  console.log(message.result);
}

query() runs Claude’s agent loop. The for await loop reads its messages; this example prints the final answer or throws if the run fails.

Run

node agent.ts

The example asks the agent to print:

Three TypeScript release changes.
Sources for the summary.
The actual tool cost, or the reason it could not complete the purchase.

To try another task, edit prompt. Include the spending you allow.

Customize permissions

allowedTools preapproves AgentMuxer calls in Claude. It does not bypass AgentMuxer payment confirmation or hide unlisted tools. Configure disallowedTools or canUseTool on your Claude agent when you need more control. The helper’s tools option sets per-tool policies, not a tool allowlist. It also accepts native timeout and alwaysLoad options. See the SDK reference for details.

Applications and keys

Manage credentials and spending limits.

Run in production

Handle deployment, failures, and tracing.

Get started

Integrations

Your application

Before you start

Customize permissions

Applications and keys

Run in production

​Before you start

​Customize permissions

Applications and keys

Run in production

Before you start

Customize permissions