`custom.yaml` catalog not working in Windows

[JohnRDOrazio]

Hello @theNetworkChuck and thank you for this boilerplate! It was able to get me started in building my own MCP server.

Few things I noticed along the way. I use Windows 11 and Docker Desktop with WSL integration.

• the WSL path ~\.docker\mcp is not used at all by Docker Desktop, it only uses %USERPROFILE/mcp on the Windows side;
• creating a custom catalog custom.yaml under %USERPROFILE/mcp/catalogs is not picked up at all by Docker Desktop, not sure if there is any way to tell it to look there too, it seems to only look at %USERPROFILE/mcp/catalogs/docker_mcp.yaml, so in the end I had to paste in the custom tool to the end of the docker_mcp.yaml file
• when restarting Docker Desktop, it seems to remove any entries that are not in a published catalog, so the custom tool running on the local Docker image needs to be re-added to docker_mcp.yaml every time Docker Desktop is restarted
• no changes need to be made to any of the Claude Desktop configuration files, the latest format allows for any new tools in the Docker MCP catalog to be picked up automatically, %APPDATA%/Roaming/Claude/claude_desktop_config.json now looks something like this:

  {
      "mcpServers": {
          "MCP_DOCKER": {
              "command": "docker",
              "args": [
                  "mcp",
                  "gateway",
                  "run"
              ],
              "env": {
                  "LOCALAPPDATA": "C:\\Users\\[USER]\\AppData\\Local",
                  "ProgramData": "C:\\ProgramData",
                  "ProgramFiles": "C:\\Program Files"
              }
          }
      }
  }

• docker mcp ... commands do not work in WSL, since the Docker MCP Toolkit is only on the Windows side, simple solution is to use docker.exe mcp ... and it will invoke the Docker MCP Toolkit from Windows

OS: Windows 11
Docker Desktop: v4.48.0
Claude Desktop: v0.14.4

[JohnRDOrazio]

I see that a similar issue had been opened: #1 . However it has been closed, but perhaps is better to leave an open issue so anyone else can see the problem, until documentation is updated.

[nicr1991]

There's another workaround for this. Within the command line (I used Powershell so this applies to windows). If you use the command docker mcp catalog create <name> it will create all the proper references needed for custom catalogs to be added.
The reason here is that there is a catalogs.json file. Within that file needs to be references to the catalogs being searched. I attempted to add to the file manually, with no success, but using the docker mcp catalog create command it works. From there you can edit the body of the new catalog yaml file from either the command line or via the gui with no issues. This tiny thing cost me HOURS, so hope it helps someone else!