> For the complete documentation index, see [llms.txt](https://docs.coupler.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.coupler.io/destinations/categories/ai/custom_mcp/common-issues.md).

# Common Issues

## Connection issues

<details>

<summary>MCP client cannot connect to Coupler.io's MCP endpoint</summary>

Verify that:

* The MCP URL and token in your client config match what Coupler.io provided
* Your MCP client supports the MCP protocol version used by Coupler.io
* Check your MCP client logs for connection errors

If you're behind a corporate firewall, you may need to allow outbound connections to Coupler.io's MCP endpoint.

</details>

<details>

<summary>Authentication fails (invalid credentials)</summary>

Double-check that:

* The personal access token and URL are entered correctly in your client config with no extra spaces
* The token hasn't been regenerated since you last configured the client
* You're using the correct authentication type (Bearer token)

If you recently regenerated the token in Coupler.io, update your MCP client config with the new token.

</details>

## Data issues

<details>

<summary>Data doesn't appear in my MCP client</summary>

Troubleshoot by:

* Checking the data flow settings in Coupler.io — look for error messages or warnings
* Verifying that your source data actually contains rows (check "Data set" wizard step to confirm)
* Confirming your MCP client is configured with the correct token and URL
* Checking your MCP client's logs to see if it's successfully querying Coupler.io's endpoint

If the data flow run shows "success" but data doesn't appear in your client, the issue is likely in your client's configuration or how it queries the MCP endpoint.

</details>

<details>

<summary>Data is incomplete or truncated</summary>

This can happen if:

* Your MCP client has limits on how much data it can consume — check its documentation
* Large text fields are being cut off by character limits

Try sending a smaller subset of columns first to isolate the problem.

</details>

{% hint style="warning" %}
If issues persist after troubleshooting, review your MCP client's documentation and logs. Coupler.io exposes data via the MCP protocol standard — problems usually lie in client configuration or connectivity rather than Coupler.io itself.
{% endhint %}


---

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