Write Operations Failing with Claude Desktop Pro - All Troubleshooting Steps Completed

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Hello! :wave: legally blind dev here: hoping you can help

I’m using the PlayCanvas MCP Server with Claude Desktop Pro on Windows, and I’m experiencing issues with write operations after trying all troubleshooting steps.

My Setup:

  • Windows PC
  • Claude Desktop with active Pro subscription (monthly plan)
  • Node.js and npm installed
  • PlayCanvas Editor MCP Extension v1.1.26 installed
  • MCP Server location: C:\Users\Ben Fox\Documents\editor-mcp-server-main
  • Chrome extension shows “CONNECTED”
  • Claude Desktop shows playcanvas as “running”

Config File (Windows format with cmd /c):

json

{
  "mcpServers": {
    "playcanvas": {
      "command": "cmd",
      "args": [
        "/c",
        "npx",
        "tsx",
        "C:\\Users\\Ben Fox\\Documents\\editor-mcp-server-main\\src\\server.ts"
      ],
      "env": {
        "PORT": "52000"
      }
    }
  }
}

What Works:

  • playcanvas:list_entities - works perfectly
  • playcanvas:query_scene_settings - works perfectly
  • All read operations succeed consistently

What Fails:

  • playcanvas:create_entities - returns “Tool execution failed”
  • playcanvas:modify_entities - returns “Tool execution failed”
  • playcanvas:duplicate_entities - returns “Tool execution failed”
  • playcanvas:create_assets - returns “Tool execution failed”
  • All write operations fail with no additional error details

Console Output (stable connection):

[WSC] Connecting to ws://localhost:52000
[WSC] Connected

Connection remains stable with no disconnects.

Troubleshooting Already Completed:

  • :white_check_mark: Upgraded to Claude Pro subscription
  • :white_check_mark: Tried both with and without cmd /c in config
  • :white_check_mark: Ensured no manual Command Prompt server running (port conflict)
  • :white_check_mark: Restarted Claude Desktop multiple times
  • :white_check_mark: Reconnected Chrome extension multiple times
  • :white_check_mark: Verified WebSocket stays connected (no disconnects)
  • :white_check_mark: Confirmed npm install completed successfully

The WebSocket connection is healthy and stable, read operations work flawlessly, but all write operations fail silently with just “Tool execution failed” and no detailed error messages.

Question: Is this a known issue with the current version? Are there any additional configuration steps or permissions needed for write operations to work on Windows with Claude Desktop Pro?

Any help would be greatly appreciated! I’m excited to use this for an accessibility-focused art gallery project.

Thanks in advance! Ben Fox