> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mcp-use.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Tools

> List and call MCP server tools

Use a ready `MCPConnection` to list and call tools.

```typescript theme={null}
import { MCPClient } from "@mcp-use/client";

const client = new MCPClient({
  mcpServers: { demo: { url: "http://localhost:3000/mcp" } },
});

try {
  const conn = await client.connect("demo");

  const tools = await conn.listTools();
  for (const tool of tools) {
    console.log(tool.name, tool.description);
  }

  const result = await conn.callTool("read_file", { path: "/tmp/a.txt" });

  if (result.isError) {
    console.error(result.content);
  } else {
    for (const block of result.content) {
      if (block.type === "text") console.log(block.text);
    }
  }
} finally {
  await client.close();
}
```

## Timeouts

Pass MCP request options as the third argument:

```typescript theme={null}
const abortController = new AbortController();

await conn.callTool(
  "long_task",
  { input: "data" },
  {
    timeout: 300_000,
    resetTimeoutOnProgress: true,
    maxTotalTimeout: 900_000,
    signal: abortController.signal,
  },
);
```

## Lazy connect

```typescript theme={null}
let conn = client.getSession("demo");
if (!conn) conn = await client.connect("demo");
await conn.callTool("echo", { message: "hello" });
```

`getSession` returns `null` when not connected. `requireSession` throws.

## Reference

[`MCPConnection`](https://mcp-use-typescript-api-reference.vercel.app/modules/_mcp-use_client.index.html#mcpconnection) — `listTools`, `callTool`, and request options.