https://retellai.com/?utm_source=discord&utm_medium=seo logo
Powered by
I am trying to set up an MCP connection for a Shop...
# ❓・ai-evy-support
c
@AI Evy I am trying to set up an MCP connection for a Shopify store, but the MCP fails with all tool calls. I did some debugging with an Agent I created to help and this was our conclusion: yes, tool invocation is currently unusable. What’s broken is the bridge between this chat’s tool-call format and your MCP server: it’s forwarding raw tool arguments (and the wrong argument schema) instead of (a) filtering to our schema and (b) wrapping in a JSON‑RPC 
tools/call
envelope. Until that bridge is fixed, every tool call will keep failing with 
-32603
.
a
Thanks for tagging me @Corey. I'll look through relevant sources and get back to you shortly.
### Answer Based on the information I have, there are known issues with MCP tool calls that other users have reported. [(1) ]() [(2) ]() Specifically, users have encountered errors like 
-32603
and "Server not initialized" when MCP tool calls fail. [(2) ]() These issues have been escalated to Retell's engineering team as potential bugs in the MCP client implementation. Recommended next steps: 1. Report to support — Please report this issue at 
support@retellai.com
with your call IDs and workspace/org ID so engineering can investigate. [(1) ]() 2. Verify your MCP server setup — Ensure your 
/mcp/manifest.json
and 
/mcp/tools
endpoints return correct data (you can test via curl) . [(3) ]() 3. Check timeout settings — When configuring your MCP server, you can set a timeout (default is 10,000 ms) . [(4) ]() 4. *Workaround (if applicable) * — If you hit "Server not initialized" errors, the suggested workaround is to force a re-handshake (initialize → initialized) before retrying the tool call. [(2) ]() Unfortunately, I don't have documentation that addresses the specific JSON-RPC envelope wrapping issue you've described. This sounds like it may require direct engineering support. Check out these potentially useful sources: - [MCP Node]() - [MCP](
/single-multi-prompt/mcp) - [Connect any AI Voice Agent to MCP with Retell AI MCP Node (Guide) ]()
​ To learn more, see the sources I considered: [[1] MCP client fails on error tool result](https://discord.com/channels/1186424376300679209/1403849159001247844) [[2] MCP Server tool calls not stable](https://discord.com/channels/1186424376300679209/1409520321450479656) [[3] Discord message from @santelo77 on 2025-08-23](https://discord.com/channels/1186424376300679209/1294891368505937952/1408888085739208727) [[4] 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) ​
Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.
c
Tool Result tool_call_id: eb82d615526d0943 "MCP error -32603: Internal error"
PreviousNext
Powered by