Agent Plugins 1.0: custom agents under com.github.copilot/agents are not discovered

[mcollier]

Describe the bug

I am creating a plugin for GitHub Copilot using the Agent Plugins 1.0 specification. The plugin includes skills and MCP servers, along with GitHub Copilot-specific custom agents.

Based on the Agent Plugins and Microsoft documentation, GitHub Copilot-specific components should be placed under the com.github.copilot namespace. My plugin has a structure similar to:

my-plugin/
├── plugin.json
├── skills/
├── mcp.json
└── com.github.copilot/
    └── agents/
        └── example-agent.agent.md

When I install the plugin using GitHub Copilot CLI, the plugin itself appears to install successfully:

• Skills from the plugin are discovered.
• MCP servers from the plugin are discovered.
• Custom agents under com.github.copilot/agents/ are not discovered.

The same documentation indicates that custom agents in the com.github.copilot namespace should be supported by GitHub Copilot CLI.

Affected version

GitHub Copilot CLI 1.0.81.

Steps to reproduce the behavior

1. Create an Agent Plugins 1.0 plugin with a root plugin.json containing the Agent Plugins 1.0 schema:

   {
     "$schema": "https://agent-plugins.org/schemas/1.0.0/plugin.schema.json",
     "name": "example-plugin",
     "version": "1.0.0"
   }

2. Add a custom agent under: com.github.copilot/agents/example-agent.agent.md

3. Optionally add a skill under skills/ and/or an MCP server in mcp.json to verify that other plugin components are loaded.

4. Install the plugin using GitHub Copilot CLI.

5. Verify that the plugin is installed and that its skills and/or MCP servers are available.

6. Check the available custom agents using /agent.

7. Observe that the agent defined under com.github.copilot/agents/ is not available.

Expected behavior

GitHub Copilot CLI should discover and load custom agents defined under com.github.copilot/agents/ for plugins using the Agent Plugins 1.0 format, consistent with the documented cross-tool compatibility behavior.

If additional configuration is required for Copilot CLI to load these agents, it would be helpful for that requirement to be documented.

Additional context

GitHub's Agent Plugins 1.0 announcement states that Copilot-specific capabilities such as custom agents, commands, rules, and hooks can be placed under com.github.copilot/ and loaded across VS Code, GitHub Copilot CLI, and the GitHub Copilot app.

The VS Code documentation specifically shows the following Agent Plugins 1.0 structure:

my-testing-plugin/
  plugin.json              # Plugin metadata and configuration
  skills/
    test-runner/
      SKILL.md             # Testing skill instructions
      run-tests.sh         # Supporting script
  mcp.json                 # MCP server definitions
  scripts/
    validate-tests.sh      # Hook script
  com.github.copilot/
    agents/
      test-reviewer.agent.md  # Code review agent
    hooks/
      hooks.json           # Hook configuration

Since GitHub Copilot CLI successfully discovers the components from the same plugin but does not discover the custom agents, this appears to be specific to loading Copilot-specific components from the com.github.copilot namespace.

References

• https://github.blog/changelog/2026-08-12-agent-plugins-1-0-in-vs-code-copilot-cli-and-the-copilot-app/
• https://code.visualstudio.com/docs/agent-customization/agent-plugins#_cross-tool-compatibility