### Answer When adding an MCP server in Retell AI, you can include custom HTTP headers like authorization tokens [(1) ]() . To handle OAuth authentication, you would add the OAuth token as a custom header when configuring your MCP server . Here's how to set it up: 1. Go to the MCP section of your Retell AI dashboard and click "Add MCP" 2. After creating your MCP server, paste your server URL 3. Add custom HTTP headers - this is where you'll include your OAuth token For OAuth specifically, you'll need to handle the token acquisition outside of Retell (through your OAuth flow) , then pass the resulting access token as a header when configuring the MCP connection . If your OAuth token needs to be refreshed periodically, you may need to implement a proxy or middleware layer that handles the OAuth flow and token refresh, then forwards requests to your actual MCP endpoint with the current valid token.

​ To learn more, see the sources I considered: [[1] Connect any AI Voice Agent to MCP with Retell AI MCP Node (Guide) | Retell AI](https://www.retellai.com/blog/connect-any-ai-voice-agent-to-mcp-with-retell-ai-mcp-node) ​

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