Why does VS Code say 'Unknown tool' for github/* in a custom agent but warn 'renamed' for github?

5 answers

• Best answerAgentArmor teamTeam4d ago

  Status: open. The thread does not show an official fix; the open issue discusses a mismatch between the config key and the server's reported name.

  What the thread reports:

  1. Rename the server key in mcp.json to github-mcp-server. One reporter said this fixed the Unknown tool error for their setup, and then referenced the server using that name:

  jsonCopy to clipboard

  "github-mcp-server": {
    "type": "http",
    "url": "https://api.githubcopilot.com/mcp/"
  }
  

  2. Install the server from the MCP marketplace instead of a manual entry. A commenter suggested searching @mcp github in the Extensions view, which should show the server with id io.github.github/github-mcp-server. Another commenter said VS Code has a built-in GitHub MCP server that can be enabled with the setting github.copilot.chat.githubMcpServer.enabled. Neither was reported as tested in this thread.

  3. Keep the agent in .github/agents. A commenter reported that older .github/chatmodes files may not handle the aliases.

  General advice: after editing mcp.json, reload the VS Code window and check the Problems panel again. A VS Code feature request (microsoft/vscode#323411) exists to improve the error messages.

  Did this work for you?WorkedDidn't work
  UpvoteStarReport
• AgentArmor teamTeam4d ago

  What a GitHub user tried on GitHub (Didn't work)

  Used "tools": ["github/*"] in a VS Code agent config with the server installed as "github"; got Unknown tool. Changing it to "github" loaded the agent but showed a rename warning.

  Source: https://github.com/github/github-mcp-server/issues/1402 (opens external site) ↗

  Did this work for you?WorkedDidn't work
  UpvoteStarReport
• AgentArmor teamTeam4d ago

  What @yurideon tried on GitHub (Worked)

  Installed via the README button, which adds a "github" http entry to mcp.json, and used "tools": ["github"] in a custom agent in .github/agents. The commenter reported the agent could access the GitHub MCP server with this entry.

  Source: https://github.com/github/github-mcp-server/issues/1402#issuecomment-3549995398 (opens external site) ↗

  Did this work for you?WorkedDidn't work
  UpvoteStarReport
• AgentArmor teamTeam4d ago

  What @aviita tried on GitHub (Didn't work)

  Used the tools picker in a chatmode file, which added github/search_repositories and produced an Unknown tool warning; going back to the picker showed the GitHub tools disabled again.

  Source: https://github.com/github/github-mcp-server/issues/1402#issuecomment-3626092830 (opens external site) ↗

  Did this work for you?WorkedDidn't work
  UpvoteStarReport
• AgentArmor teamTeam4d ago

  What @aviita tried on GitHub (Worked)

  Renamed the MCP server key in mcp.json to github-mcp-server to match the server's reported name. The commenter said this fixed it, though tools picker behavior had seemed fine before the rename.

  Source: https://github.com/github/github-mcp-server/issues/1402#issuecomment-3626127948 (opens external site) ↗

  Did this work for you?WorkedDidn't work
  UpvoteStarReport