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

# Claude Desktop

> Set up Isthmus with Claude Desktop on macOS and Windows.

## Config file location

<Tabs>
  <Tab title="macOS">
    ```
    ~/Library/Application Support/Claude/claude_desktop_config.json
    ```
  </Tab>

  <Tab title="Windows">
    ```
    %APPDATA%\Claude\claude_desktop_config.json
    ```
  </Tab>
</Tabs>

## Minimal configuration

Add Isthmus to the `mcpServers` object:

```json theme={null}
{
  "mcpServers": {
    "isthmus": {
      "command": "isthmus",
      "env": {
        "DATABASE_URL": "postgres://user:password@localhost:5432/mydb"
      }
    }
  }
}
```

## Full configuration

Include optional settings for schema filtering, policy enrichment, and row limits:

```json theme={null}
{
  "mcpServers": {
    "isthmus": {
      "command": "isthmus",
      "args": ["--audit-log", "/tmp/isthmus-audit.ndjson"],
      "env": {
        "DATABASE_URL": "postgres://user:password@localhost:5432/mydb",
        "SCHEMAS": "public,analytics",
        "POLICY_FILE": "/path/to/policy.yaml",
        "MAX_ROWS": "500"
      }
    }
  }
}
```

## Verify

1. Save the config file
2. Restart Claude Desktop (Cmd+Q, then reopen)
3. Look for the MCP tools icon in the chat input area
4. Ask: **"What tables are in my database?"**

Claude should call `discover` and return a summary of your database.

## Troubleshooting

<AccordionGroup>
  <Accordion title="Binary not found">
    Claude Desktop needs `isthmus` in your PATH. Check where it's installed:

    ```bash theme={null}
    which isthmus
    ```

    If it's not in your PATH, use the full path in the config. The location depends on how you installed:

    * **Install script / prebuilt binary:** `/usr/local/bin/isthmus`
    * **go install:** `~/go/bin/isthmus`

    ```json theme={null}
    "command": "/usr/local/bin/isthmus"
    ```
  </Accordion>

  <Accordion title="Wrong config file path">
    On macOS, the config file must be at exactly:

    ```
    ~/Library/Application Support/Claude/claude_desktop_config.json
    ```

    Create the file if it doesn't exist. Make sure it's valid JSON.
  </Accordion>

  <Accordion title="Database unreachable">
    Test connectivity outside Claude Desktop first:

    ```bash theme={null}
    DATABASE_URL="postgres://user:password@localhost:5432/mydb" isthmus --dry-run
    ```

    If this fails, check your connection string, network, and Postgres status.
  </Accordion>
</AccordionGroup>