Troubleshooting Agents
Troubleshoot common issues with Agents.
MCP Connection Error
Pipeline Tool Shows Validation Warnings
When you add a pipeline as a tool, deepset validates the pipeline before adding it. If the pipeline has non-fatal validation issues (warnings), the tool is still added to the Agent. The warnings are stored on the tool and are visible in the tool configuration.
Warnings do not prevent the tool from being used, but you should review them to make sure the pipeline behaves as expected. To inspect the warnings, open the tool configuration in the Agent's Tools panel.
If you see a hard validation error and the tool was not added, the pipeline has an issue that prevents it from being used as a tool. Open the pipeline in Builder, check the Issues panel for errors, and resolve them before trying to add the tool again. Click Inspect next to any error to jump to the affected component, or click Fix with AI to open the AI assistant, which reasons through the fix and can apply it for you.
Tool Description Is Not a Valid String
Symptoms: Your pipeline returns an error that includes text like custom.description: Input should be a valid string when the Agent uses an Anthropic model.
What happens: Anthropic validates every tool definition sent with a request. If a tool in the Agent's tool list has a description field that isn't a valid string — for example, it's empty, set to None, or set to a non-string value — Anthropic rejects the request with an HTTP 400 error, and the pipeline run fails.
Solution:
- Open your pipeline in Pipeline Builder and find the Agent component.
- In the Agent's Tools panel, review each tool, including any pipelines added as tools.
- Make sure every tool has a non-empty string description.
- Save and redeploy the pipeline.
For more information on configuring tools, see Agent Tools and Configure an Agent.
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