Open Agent SDK (TypeScript)

Open-source Agent SDK that runs the full agent loop in-process — no subprocess or CLI required. Deploy anywhere: cloud, serverless, Docker, CI/CD.

Also available in Go: open-agent-sdk-go

Get started

npm install @codeany/open-agent-sdk

Set your API key:

export CODEANY_API_KEY=your-api-key

Third-party providers (e.g. OpenRouter) are supported via CODEANY_BASE_URL:

export CODEANY_BASE_URL=https://openrouter.ai/api
export CODEANY_API_KEY=sk-or-...
export CODEANY_MODEL=anthropic/claude-sonnet-4

Quick start

One-shot query (streaming)

import { query } from "@codeany/open-agent-sdk";

for await (const message of query({
  prompt: "Read package.json and tell me the project name.",
  options: {
    allowedTools: ["Read", "Glob"],
    permissionMode: "bypassPermissions",
  },
})) {
  if (message.type === "assistant") {
    for (const block of message.message.content) {
      if ("text" in block) console.log(block.text);
    }
  }
}

Simple blocking prompt

import { createAgent } from "@codeany/open-agent-sdk";

const agent = createAgent({ model: "claude-sonnet-4-6" });
const result = await agent.prompt("What files are in this project?");

console.log(result.text);
console.log(
  `Turns: ${result.num_turns}, Tokens: ${result.usage.input_tokens + result.usage.output_tokens}`,
);

Multi-turn conversation

import { createAgent } from "@codeany/open-agent-sdk";

const agent = createAgent({ maxTurns: 5 });

const r1 = await agent.prompt(
  'Create a file /tmp/hello.txt with "Hello World"',
);
console.log(r1.text);

const r2 = await agent.prompt("Read back the file you just created");
console.log(r2.text);

console.log(`Session messages: ${agent.getMessages().length}`);

Custom tools (Zod schema)

import { z } from "zod";
import { query, tool, createSdkMcpServer } from "@codeany/open-agent-sdk";

const getWeather = tool(
  "get_weather",
  "Get the temperature for a city",
  { city: z.string().describe("City name") },
  async ({ city }) => ({
    content: [{ type: "text", text: `${city}: 22°C, sunny` }],
  }),
);

const server = createSdkMcpServer({ name: "weather", tools: [getWeather] });

for await (const msg of query({
  prompt: "What is the weather in Tokyo?",
  options: { mcpServers: { weather: server } },
})) {
  if (msg.type === "result")
    console.log(`Done: $${msg.total_cost_usd?.toFixed(4)}`);
}

Custom tools (low-level)

import {
  createAgent,
  getAllBaseTools,
  defineTool,
} from "@codeany/open-agent-sdk";

const calculator = defineTool({
  name: "Calculator",
  description: "Evaluate a math expression",
  inputSchema: {
    type: "object",
    properties: { expression: { type: "string" } },
    required: ["expression"],
  },
  isReadOnly: true,
  async call(input) {
    const result = Function(`'use strict'; return (${input.expression})`)();
    return `${input.expression} = ${result}`;
  },
});

const agent = createAgent({ tools: [...getAllBaseTools(), calculator] });
const r = await agent.prompt("Calculate 2**10 * 3");
console.log(r.text);

MCP server integration

import { createAgent } from "@codeany/open-agent-sdk";

const agent = createAgent({
  mcpServers: {
    filesystem: {
      command: "npx",
      args: ["-y", "@modelcontextprotocol/server-filesystem", "/tmp"],
    },
  },
});

const result = await agent.prompt("List files in /tmp");
console.log(result.text);
await agent.close();

Subagents

import { query } from "@codeany/open-agent-sdk";

for await (const msg of query({
  prompt: "Use the code-reviewer agent to review src/index.ts",
  options: {
    agents: {
      "code-reviewer": {
        description: "Expert code reviewer",
        prompt: "Analyze code quality. Focus on security and performance.",
        tools: ["Read", "Glob", "Grep"],
      },
    },
  },
})) {
  if (msg.type === "result") console.log("Done");
}

Permissions

import { query } from "@codeany/open-agent-sdk";

// Read-only agent — can only analyze, not modify
for await (const msg of query({
  prompt: "Review the code in src/ for best practices.",
  options: {
    allowedTools: ["Read", "Glob", "Grep"],
    permissionMode: "dontAsk",
  },
})) {
  // ...
}

Web UI

A built-in web chat interface is included for testing:

npx tsx examples/web/server.ts
# Open http://localhost:8081

API reference

Top-level functions

Agent methods

Options

Environment variables

Built-in tools

Architecture

┌──────────────────────────────────────────────────────┐
│                   Your Application                    │
│                                                       │
│   import { createAgent } from '@codeany/open-agent-sdk' │
└────────────────────────┬─────────────────────────────┘
                         │
              ┌──────────▼──────────┐
              │       Agent         │  Session state, tool pool,
              │  query() / prompt() │  MCP connections
              └──────────┬──────────┘
                         │
              ┌──────────▼──────────┐
              │    QueryEngine      │  Agentic loop:
              │   submitMessage()   │  API call → tools → repeat
              └──────────┬──────────┘
                         │
         ┌───────────────┼───────────────┐
         │               │               │
   ┌─────▼─────┐  ┌─────▼─────┐  ┌─────▼─────┐
   │  LLM API  │  │  34 Tools │  │    MCP     │
   │  Client   │  │ Bash,Read │  │  Servers   │
   │ (streaming)│  │ Edit,...  │  │ stdio/SSE/ │
   └───────────┘  └───────────┘  │ HTTP/SDK   │
                                  └───────────┘

Key internals:

Examples

Run any example:

npx tsx examples/01-simple-query.ts

Start the web UI:

npx tsx examples/web/server.ts

Star History

License

MIT