---
title: Debugging the MCP Server
---


## Debugging with MCP Inspector

[MCP Inspector](https://modelcontextprotocol.io/docs/tools/inspector) is a debugging tool for MCP servers.

### Debug locally over stdio transport

You can inspect a local Apollo MCP Server by running it with MCP Inspector.

1. Run the MCP Server with Inspector:

```yaml title="Example config for debugging over stdio"
operations:
  source: local
  paths:
    - <absolute path to this git repo>/graphql/weather/operations/
schema:
  source: local
  path: <absolute path to this git repo>/graphql/weather/api.graphql
transport:
  type: stdio
```

```sh
npx @modelcontextprotocol/inspector \
  target/debug/apollo-mcp-server <path to the preceding config>
```

<ExpansionPanel title="Example output">

```sh showLineNumbers=false disableCopy=true
Starting MCP inspector...
⚙️ Proxy server listening on port 6277
🔍 MCP Inspector is up and running at http://127.0.0.1:6274 🚀
```

</ExpansionPanel>

1. In a browser, go to the URL returned by Inspector, then click **Connect** and **List Tools**. You should see the tools for the operations you provided.

### Debug over the Streamable HTTP transport

When running the MCP Server over the Streamable HTTP transport, you can run MCP Inspector as follows.

1. Start the MCP Server in Streamable HTTP mode:

<Tip>

You can also deploy the server as a container using the instructions in [Deploying a Container](#deploying-a-container).

</Tip>

```yaml title="Example config for running in Streamable HTTP"
operations:
  source: local
  paths:
    - <absolute path to this git repo>/graphql/weather/operations/
schema:
  source: local
  path: <absolute path to this git repo>/graphql/weather/api.graphql
transport:
  type: streamable_http
  address: 127.0.0.1
  port: 8000
```

```sh
target/debug/apollo-mcp-server <path to the above config>
```

1. Start the MCP Inspector:

```sh
npx @modelcontextprotocol/inspector
```

1. In a browser, go to the URL returned by Inspector, then fill in the details:

   - **Transport Type**: Select `Streamable HTTP`
   - **URL**: Enter `http://127.0.0.1:8000/mcp`, where the port must match the `transport.port` option

1. Click **Connect** and **List Tools**. You should see the tools for the operations you provided.
