mcp-server Example in Custom Agents Documenation

[smaglio81]

🏷️ Discussion Type

Product Feedback

💬 Feature/Topic Area

Copilot Coding Agent

Body

Could the About Custom Agents page be updated to include an example using the mcp-server property?

My gut feeling is that the property would want the json formatted MCP definition (example below), but I've found that frontmatter is very particular about only accepting single line strings.

So, I'm hoping that the documentation could provide an example?

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

Also, could the documentation list if you can use secrets stored in a repository to populate tokens, like in thes example below?

If you defined an agent in the organization level .github-private repo, would you be able to define the secret in that repo, and the secret would be injected whenever the agent is used in the individual repositories?

{
  "servers": {
    "github": {
      "type": "http",
      "url": "https://api.githubcopilot.com/mcp/",
      "headers": {
        "Authorization": "Bearer ${input:github_mcp_pat}"
      }
    }
  },
  "inputs": [
    {
      "type": "promptString",
      "id": "github_mcp_pat",
      "description": "GitHub Personal Access Token",
      "password": true
    }
  ]
}

[github-actions[bot]]

💬 Your Product Feedback Has Been Submitted 🎉

Thank you for taking the time to share your insights with us! Your feedback is invaluable as we build a better GitHub experience for all our users.

Here's what you can expect moving forward ⏩

• Your input will be carefully reviewed and cataloged by members of our product teams. 
  • Due to the high volume of submissions, we may not always be able to provide individual responses.
  • Rest assured, your feedback will help chart our course for product improvements.
• Other users may engage with your post, sharing their own perspectives or experiences. 
• GitHub staff may reach out for further clarification or insight. 
  • We may 'Answer' your discussion if there is a current solution, workaround, or roadmap/changelog post related to the feedback.

Where to look to see what's shipping 👀

• Read the Changelog for real-time updates on the latest GitHub features, enhancements, and calls for feedback.
• Explore our Product Roadmap, which details upcoming major releases and initiatives.

What you can do in the meantime 💻

• Upvote and comment on other user feedback Discussions that resonate with you.
• Add more information at any point! Useful details include: use cases, relevant labels, desired outcomes, and any accompanying screenshots.

As a member of the GitHub community, your participation is essential. While we can't promise that every suggestion will be implemented, we want to emphasize that your feedback is instrumental in guiding our decisions and priorities.

Thank you once again for your contribution to making GitHub even better! We're grateful for your ongoing support and collaboration in shaping the future of our platform. ⭐

[asaddevx]

Hi @smagli081, great question! This is an area where the documentation could definitely use more clarity.

1. Using mcp-server with Frontmatter

You're correct that frontmatter can be picky about multi-line strings. The mcp-server property expects a valid JSON object. Here are two reliable ways to format it:

Option A: Single-line JSON (most reliable)

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

Option B: YAML literal block (more readable)

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

Both work. Option A is more compact; Option B is easier to read and maintain.

2. Using Secrets with MCP Servers

For the secrets injection pattern you're showing, you have two approaches depending on your use case:

Approach A: Prompt user at runtime (your example)

{
  "servers": {
    "github": {
      "type": "http",
      "url": "https://api.githubcopilot.com/mcp/",
      "headers": {
        "Authorization": "Bearer ${input:github_mcp_pat}"
      }
    }
  },
  "inputs": [
    {
      "type": "promptString",
      "id": "github_mcp_pat",
      "description": "GitHub Personal Access Token",
      "password": true
    }
  ]
}

This works well when you want each user to provide their own token at execution time.

Approach B: Use GitHub Secrets (automated)
If you want the token injected automatically without prompting, use GitHub Secrets syntax:

{
  "servers": {
    "github": {
      "type": "http",
      "url": "https://api.githubcopilot.com/mcp/",
      "headers": {
        "Authorization": "Bearer ${{ secrets.GITHUB_MCP_PAT }}"
      }
    }
  }
}

3. Organization-Level Secrets

Regarding your question about .github-private and organization-level agents:

• Organization secrets work across all repositories in the organization if you set the secret's visibility to "selected repositories" or "all repositories"
• When defining an agent at the organization level (in .github-private), organization secrets are available for injection
• Individual repositories don't need to define the secret separately if the organization secret is configured to be available to them

4. Documentation Feedback

Since this is a documentation enhancement request, here's how to get it to the right people:

1. Open an issue in the github/docs repository
2. Select "Docs feedback" as the issue type
3. Reference this discussion and include the example formats above

The docs team actively monitors that repository and regularly updates the documentation based on community feedback.

---

Hope this helps! Let me know if you need clarification on any of these approaches.

---