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The @mcpjam/sdk is a TypeScript SDK for testing, evaluating, and building applications with MCP (Model Context Protocol) servers. It provides everything you need to ensure your MCP server works reliably across different LLMs and environments.

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Who is this for?

  • MCP Server Developers - Test your tools work correctly with real LLMs
  • MCP Client Developers - Build robust multi-server applications
  • App Marketplace Maintainers - Evaluate server quality and compatibility
  • SDK Developers - Integrate MCP capabilities into your products

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What can you do with it?

Unit Testing

Test MCP primitives (tools, resources, prompts) deterministically without LLM calls

End-to-End Testing

Simulate real user interactions by connecting LLMs to your MCP servers

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Installation

npm install @mcpjam/sdk

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Quick Example

import { MCPClientManager, TestAgent, EvalTest } from "@mcpjam/sdk";

// Connect to your MCP server
const manager = new MCPClientManager({
  myServer: {
    command: "npx",
    args: ["-y", "@modelcontextprotocol/server-everything"],
  },
});

// Create an agent with LLM + MCP tools
const agent = new TestAgent({
  tools: await manager.getTools(),
  model: "anthropic/claude-sonnet-4-20250514",
  apiKey: process.env.ANTHROPIC_API_KEY,
});

// Run a prompt and inspect results
const result = await agent.prompt("Add 2 and 3");
console.log(result.toolsCalled());     // ["add"]
console.log(result.e2eLatencyMs());    // 1234

// Run statistical evaluation
const test = new EvalTest({
  name: "addition",
  test: async (agent) => {
    const r = await agent.prompt("Add 2+3");
    return r.hasToolCall("add");
  },
});
await test.run(agent, { iterations: 30 });
console.log(`Accuracy: ${(test.accuracy() * 100).toFixed(1)}%`);