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i set up claude_desktop_config
# ❓・ai-evy-support
t
@AI Evy i set up claude_desktop_config.json using the details needed { "mcpServers": { "retellai-mcp-server": { "command": "npx", "args": [ "-y", "@abhaybabbar/retellai-mcp-server" ], "env": { "RETELL_API_KEY": "" } } } } but when i restart my claude application on windows i don't see the mcp server ,what's happening?
a
Thanks for tagging me @trx598. I'll look through relevant sources and get back to you shortly.
### Answer The issue is likely that Node.js is not installed or npx is not in your system PATH on Windows. [(1) ]() The error 
spawn npx ENOENT
means your system can't find npx. To fix this on Windows: 1. Install Node.js so that 
node
, 
npm
, and 
npx
are available on your system. 2. Update your config to use the Windows command format:
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json
{
  "mcpServers": {
    "retellai-mcp-server": {
      "command": "cmd",
      "args": ["/c", "npx", "-y", "@abhaybabbar/retellai-mcp-server"],
      "env": {
        "RETELL_API_KEY": "your_actual_api_key_here"
      }
    }
  }
}
3. Make sure your RETELL_API_KEY is filled in — your config shows an empty string for the API key, which would also prevent the server from working properly. After installing Node.js and updating the config, restart Claude and the MCP server should appear. For additional setup resources, see: - [Retell MCP Server Package (NPM) ]() [(2) ]() - [Retell MCP Server Repository (Github) ]()
​ To learn more, see the sources I considered: [[1] MCP server connection between Retell and Claude](https://discord.com/channels/1186424376300679209/1374739679487852594) [[2] How to Connect Retell AI MCP Server to Claude & More | Retell AI | Retell AI](https://www.retellai.com/blog/connect-retell-ai-mcp-server-to-ai-assistant) ​
Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.
t
@AI Evy i see it now but when i tap switch it on ,it doesn't switch on\
a
Thanks for the follow-up, @trx598. I'll get back to you soon.
### Answer If the MCP server appears in Claude but won't switch on, here are the most common causes: 1. Your RETELL_API_KEY is empty or invalid Your earlier config showed an empty string for the API key:
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json
"env": {
    "RETELL_API_KEY": ""
}
You need to add your actual Retell API key (found in your Retell dashboard) for the server to authenticate and start properly. 2. Check Claude's MCP logs for errors In Claude Desktop, you can usually view logs or error messages that explain why the server failed to start. Look for authentication errors or connection issues. 3. Verify Node.js/npx is working correctly Open a terminal and run:
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npx -y @abhaybabbar/retellai-mcp-server
If this fails or shows errors, there may be a package installation issue. 4. Try restarting Claude completely After updating your config with a valid API key, fully quit Claude (not just close the window) and reopen it. The available sources don't provide specific troubleshooting steps for the Claude Desktop MCP toggle not working. I'd recommend checking the [Retell MCP Server Repository (Github) ]() for any Windows-specific issues or opening a support ticket. Would you like a general answer based on my knowledge of MCP server troubleshooting?
Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.
message has been deleted
t
@AI Evy C:\Users\PC\Documents>npx -y @abhaybabbar/retellai-mcp-server Error starting MCP server: Error: RETELL_API_KEY environment variable is required at createMcpServer (file:///C:/Users/PC/AppData/Local/npm-cache/_npx/51761a637effe463/node_modules/@abhaybabbar/retellai-mcp-server/build/index.js:11:15) at main (file:///C:/Users/PC/AppData/Local/npm-cache/_npx/51761a637effe463/node_modules/@abhaybabbar/retellai-mcp-server/build/index.js:24:27) at file:///C:/Users/PC/AppData/Local/npm-cache/_npx/51761a637effe463/node_modules/@abhaybabbar/retellai-mcp-server/build/index.js:46:1 at ModuleJob.run (node:internal/modules/esm/module_job:274:25) at async onImport.tracePromise.__proto__ (node:internal/modules/esm/loader:644:26) at async asyncRunEntryPointWithESMLoader (node:internal/modules/run_main:117:5)
a
Thanks for the follow-up, @trx598. I'll get back to you soon.
### Answer The error confirms the issue: your RETELL_API_KEY is missing. The MCP server requires a valid API key to start. [(1) ]() To fix this: 1. Get your API key from your Retell AI dashboard (navigate to the "API Keys" tab) . [(2) ]() 2. Update your 
claude_desktop_config.json
 with your actual API key:
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json
{
  "mcpServers": {
    "retellai-mcp-server": {
      "command": "cmd",
      "args": ["/c", "npx", "-y", "@abhaybabbar/retellai-mcp-server"],
      "env": {
        "RETELL_API_KEY": "YOUR_ACTUAL_API_KEY_HERE"
      }
    }
  }
}
[(3) ]() 3. Replace 
YOUR_ACTUAL_API_KEY_HERE
 with your real Retell API key (it typically starts with 
key_
) . 4. Save the file and restart Claude completely (quit and reopen the application) . [(1) ]() Once you add a valid API key, the MCP server should start and the toggle should work.
​ To learn more, see the sources I considered: [[1] How to Connect Retell AI MCP Server to Claude & More | Retell AI | Retell AI](https://www.retellai.com/blog/connect-retell-ai-mcp-server-to-ai-assistant) [[2] SDKs](https://docs.retellai.com/get-started/sdk) [[3] MCP server connection between Retell and Claude](https://discord.com/channels/1186424376300679209/1374739679487852594) ​
Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.
t
where is or where should it be located?claude_desktop_config.json
@AI Evy where is or where should it be located?claude_desktop_config.json
a
Thanks for the follow-up, @trx598. I'll get back to you soon.
### Answer The available Retell AI documentation doesn't specify the exact file path for 
claude_desktop_config.json
— this is a Claude Desktop configuration file, not a Retell AI file. [(1) ]() However, based on standard Claude Desktop behavior on Windows, the config file is typically located at:
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%APPDATA%\Claude\claude_desktop_config.json
Which usually resolves to:
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C:\Users\<YourUsername>\AppData\Roaming\Claude\claude_desktop_config.json
To access it: 1. Press 
Win + R
2. Type 
%APPDATA%\Claude
and press Enter 3. Look for 
claude_desktop_config.json
in that folder If the file doesn't exist, you may need to create it manually in that location. For Claude-specific configuration details, I'd recommend checking Claude's official documentation, as this falls outside of Retell AI's scope.
​ To learn more, see the sources I considered: [[1] How to Connect Retell AI MCP Server to Claude & More | Retell AI | Retell AI](https://www.retellai.com/blog/connect-retell-ai-mcp-server-to-ai-assistant) ​
Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.
t
the env is aleady set but i still get that error
@AI Evy the { "mcpServers": { "retellai-mcp-server": { "command": "cmd", "args": [ "/c", "npx", "-y", "@abhaybabbar/retellai-mcp-server" ], "env": { "RETELL_API_KEY": "key_" } } } } i already set it ,
a
Thanks for the follow-up, @trx598. I'll get back to you soon.
### Answer Your config shows 
"RETELL_API_KEY": "key_"
— this appears to be incomplete. You need to include your full API key, not just the prefix 
key_
. [(1) ]() Your complete API key should look something like 
key_abc123xyz456...
(a longer string after 
key_
) . To get your full API key: Navigate to the "API Keys" tab in your Retell AI dashboard to obtain your complete API key. Also note: There's a known bug with the 
@abhaybabbar/retellai-mcp-server
package that causes a Zod-related error (
Unable to read undefined properties (reading '_zod')
) . [(2) ]() , [(3) ]() If you continue having issues after adding your full API key, try using an alternative package instead: [(2) ]() , [(3) ]()
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json
{
  "mcpServers": {
    "retell": {
      "command": "npx",
      "args": ["-y", "@jesec/retellai-mcp-server"],
      "env": {
        "RETELL_API_KEY": "YOUR_FULL_RETELL_KEY_HERE"
      }
    }
  }
}
[(2) ]() , [(3) ]() Replace 
YOUR_FULL_RETELL_KEY_HERE
with your complete API key from the dashboard.
​ To learn more, see the sources I considered: [[1] SDKs](https://docs.retellai.com/get-started/sdk) [[2] Discord message from @mroverworked on 2026-01-02](https://discord.com/channels/1186424376300679209/1186462578310910112/1456456066899513414) [[3] Discord message from @mroverworked on 2026-01-02](https://discord.com/channels/1186424376300679209/1186462578310910112/1456446543891795970) ​
Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.
t
@AI Evy And so how do we run with that one @jesec/retellai-mcp-server
a
Thanks for the follow-up, @trx598. I'll get back to you soon.
### Answer To use the 
@jesec/retellai-mcp-server
package on Windows, update your 
claude_desktop_config.json
with this configuration: [(1) ]()
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json
{
  "mcpServers": {
    "retell": {
      "command": "npx",
      "args": ["-y", "@jesec/retellai-mcp-server"],
      "env": {
        "RETELL_API_KEY": "YOUR_RETELL_KEY_HERE"
      }
    }
  }
}
Steps: 1. Replace 
YOUR_RETELL_KEY_HERE
with your complete API key from your Retell AI dashboard (found in the "API Keys" tab) . [(2) ]() 2. Save the config file. 3. Fully quit Claude Desktop (not just close the window) and reopen it. [(3) ]() The 
@jesec/retellai-mcp-server
is an alternative package that resolves the Zod-related bug in the original 
@abhaybabbar/retellai-mcp-server
package. [(1) ]() After restarting Claude, the Retell MCP server should appear in your tools list and the toggle should work.
​ To learn more, see the sources I considered: [[1] Discord message from @mroverworked on 2026-01-02](https://discord.com/channels/1186424376300679209/1186462578310910112/1456446543891795970) [[2] SDKs](https://docs.retellai.com/get-started/sdk) [[3] How to Connect Retell AI MCP Server to Claude & More | Retell AI | Retell AI](https://www.retellai.com/blog/connect-retell-ai-mcp-server-to-ai-assistant) ​
Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.
t
@AI Evy I try to start teh radio button in claude but it still isn't working ,can we debug it by running this?"npx", "args": ["-y", "@jesec/retellai-mcp-server"], "env": {
a
Thanks for the follow-up, @trx598. I'll get back to you soon.
### Answer Yes, you can debug by running the command directly in your terminal. Open Command Prompt or PowerShell and run:
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npx -y @jesec/retellai-mcp-server
Important: You need to set the environment variable first. On Windows, run this before the npx command:
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set RETELL_API_KEY=your_full_api_key_here
npx -y @jesec/retellai-mcp-server
[(1) ]() Replace 
your_full_api_key_here
with your complete Retell API key from your dashboard. [(2) ]() If the server starts successfully in the terminal, the issue is with how Claude Desktop reads the config. If it fails, the error message will tell you what's wrong. Common issues to check: - Make sure your API key is the complete key (not just 
key_
but the full string like 
key_abc123...
) - On Windows, you may need to use the 
cmd
format in your config:
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json
{
  "mcpServers": {
    "retell": {
      "command": "cmd",
      "args": ["/c", "npx", "-y", "@jesec/retellai-mcp-server"],
      "env": {
        "RETELL_API_KEY": "your_full_api_key_here"
      }
    }
  }
}
[(1) ]() After updating, fully quit Claude (not just close) and reopen it. [(2) ]()
​ To learn more, see the sources I considered: [[1] MCP server connection between Retell and Claude](https://discord.com/channels/1186424376300679209/1374739679487852594) [[2] How to Connect Retell AI MCP Server to Claude & More | Retell AI | Retell AI](https://www.retellai.com/blog/connect-retell-ai-mcp-server-to-ai-assistant) ​
Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.
t
@AI Evy I Think it worked can you check?C:\Users\PC\AppData\Roaming\Claude>npx -y @jesec/retellai-mcp-server npm warn deprecated node-domexception@1.0.0: Use your platform's native DOMException instead
a
Thanks for the follow-up, @trx598. I'll get back to you soon.
### Answer That looks promising! The deprecation warning about 
node-domexception
is just a minor npm warning and doesn't affect functionality — it's safe to ignore. The fact that the command ran without throwing an error (like the 
RETELL_API_KEY environment variable is required
error you saw before) suggests the server is starting correctly. To confirm it's fully working: 1. Now restart Claude Desktop completely (quit and reopen the application) [(1) ]() 2. Click on "Search and Tools" in Claude — you should see the Retell AI MCP server listed , [(2) ](

▾

) 3. Try toggling it on — it should work now 4. Test by asking Claude something like "Can you list all the phone numbers I have in Retell?" or "Can you list my agents?" to verify the connection is working If the toggle now switches on and Claude can interact with your Retell account, you're all set!
​ To learn more, see the sources I considered: [[1] How to Connect Retell AI MCP Server to Claude & More | Retell AI | Retell AI](https://www.retellai.com/blog/connect-retell-ai-mcp-server-to-ai-assistant) [[2] Retell MCP Server Tutorial](

https://www.youtube.com/watch?v=ZTAFX0oOYhY▾

) ​
Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.
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