|
| 1 | +--- |
| 2 | +title: LangWatch MCP Server |
| 3 | +sidebarTitle: LangWatch MCP |
| 4 | +--- |
| 5 | + |
| 6 | +The [LangWatch MCP Server](https://www.npmjs.com/package/@langwatch/mcp-server) is a tool designed to aid finding, searching, and looking up LLM traces from the LangWatch platform via the [Model Context Protocol](https://modelcontextprotocol.io/introduction). |
| 7 | + |
| 8 | +This server facilitates LLM development by allowing the agent to search for traces, understand all the steps in between a problematic output and try to fix the issue. |
| 9 | + |
| 10 | +<iframe |
| 11 | + width="720" |
| 12 | + height="460" |
| 13 | + src="https://www.youtube.com/embed/ZPaG9H-N0uY" |
| 14 | + title="YouTube video player" |
| 15 | + frameborder="0" |
| 16 | + allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" |
| 17 | + allowFullScreen |
| 18 | +></iframe> |
| 19 | + |
| 20 | +## Setup in your Codebase |
| 21 | + |
| 22 | +Check out [the integration guides](/integration/overview) to start tracking your agents so both you and Cursor/Windsurf/Claude Code or your favorite coding assistant can debug it. |
| 23 | + |
| 24 | +## Setup in Cursor 👩💻 |
| 25 | + |
| 26 | +1. Navigate to the Cursor Settings |
| 27 | +2. Navigate to the MCP item in the sidebar |
| 28 | +3. Set the "name" as "LangWatch" |
| 29 | +4. Set the "type" to `command` |
| 30 | +5. Set the "command" to `npx -y @langwatch/mcp-server --apiKey=sk-lw-...` |
| 31 | +- `--apiKey`: Your LangWatch API key. This is mandatory and must be provided. |
| 32 | +- `--endpoint`: *Optional* The endpoint for the LangWatch API. Defaults to `https://app.langwatch.ai` if not specified. |
| 33 | + |
| 34 | +> [!TIP] |
| 35 | +> To aid in securing your keys, the MCP will first look at the global system environment variables `LANGWATCH_API_KEY` and `LANGWATCH_ENDPOINT` to check if they have values as well as looking at arguments passed into the server on start. |
| 36 | +
|
| 37 | +<img alt="LangWatch MCP Setup" src="https://github.com/langwatch/langwatch/raw/main/assets/mcp-server/cursor-setup.light.webp" width="900" /> |
| 38 | + |
| 39 | +## Tools |
| 40 | + |
| 41 | +The MCP Server provides the following tools: |
| 42 | + |
| 43 | +### `get_latest_traces` |
| 44 | + |
| 45 | +- **Description:** Retrieves the latest LLM traces. |
| 46 | +- **Parameters:** |
| 47 | + - `pageOffset` (optional): The page offset for pagination. |
| 48 | + - `daysBackToSearch` (optional): The number of days back to search for traces. Defaults to 1. |
| 49 | + |
| 50 | +### `get_trace_by_id` |
| 51 | + |
| 52 | +- **Description:** Retrieves a specific LLM trace by its ID. |
| 53 | +- **Parameters:** |
| 54 | + - `id`: The ID of the trace to retrieve. |
| 55 | + |
| 56 | +## Usage in Cursor |
| 57 | + |
| 58 | +To use these tools within Cursor, follow these steps: |
| 59 | + |
| 60 | +1. **Open the Cursor Chat view:** |
| 61 | + - `Cmd + I` |
| 62 | + |
| 63 | +2. **Ensure the MCP server is running:** |
| 64 | + |
| 65 | +3. **Interact with your Agent:** |
| 66 | + - Ask a question like the following to test the tools are accessible: *Note: When the tool is detected, you'll need to run `Run tool` in the chat view for it to be called. |
| 67 | + |
| 68 | +> "I just ran into an issue while debugging, can you check the latest traces and fix it?" |
| 69 | +
|
| 70 | +<img alt="LangWatch MCP Example" src="https://github.com/langwatch/langwatch/raw/main/assets/mcp-server/cursor-example.light.webp" width="900" /> |
| 71 | + |
| 72 | + |
| 73 | +## 🛟 Support |
| 74 | + |
| 75 | +If you have questions or need help, join our community: |
| 76 | + |
| 77 | +- [Discord Community](https://discord.gg/kT4PhDS2gH) |
| 78 | +- [Email Support](mailto:support@langwatch.ai) |
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