Support configuring custom MCP server endpoint (mcp-server-url input)

[cogni-ai-ee]

Summary

Add support for configuring a custom MCP (Model Context Protocol) server endpoint in the AI Inference action, via a new input (e.g. mcp-server-url).

Motivation

Currently, the action only connects to the hardcoded GitHub-hosted MCP server (https://api.githubcopilot.com/mcp/) for tool/skill integration. There is no way to register or connect to a custom/self-hosted MCP server. This limits extensibility for organizations or developers running their own MCP infrastructure, custom tool registries, or private skill catalogs.

Enabling this feature would allow users to:

• Point the action to a custom MCP server for tool/skill/service integration
• Use in-house or extended toolsets not available on the official GitHub MCP instance
• Develop/test new tools before publishing to a wider audience
• Integrate with alternative MCP implementations or future standard-compliant endpoints

Proposed Solution

• Add a new optional input to action.yml:

  inputs:
    mcp-server-url:
      description: The MCP server URL to connect to
      required: false
      default: 'https://api.githubcopilot.com/mcp/'

• Refactor action source (src/mcp.ts, src/main.ts) to:
  • Use mcp-server-url for the MCP endpoint instead of the hardcoded URL
  • Maintain backward compatibility if the input is not provided (default to GitHub MCP)
  • Pass all relevant auth tokens/headers as done for the official server
• Update documentation and usage examples

Example usage

steps:
  - name: Run AI Inference with Custom MCP
    uses: actions/ai-inference@v2
    with:
      prompt: 'What open PRs have the most review comments?'
      enable-github-mcp: true
      github-mcp-token: ${{ secrets.USER_PAT }}
      mcp-server-url: 'https://mcp.internal.myorg.com/'

Acceptance Criteria

• A new mcp-server-url input is available and documented
• Action connects to the specified server for tool discovery and execution
• Existing workflows using the default remain compatible
• Tests exercise the custom server input

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Related feature area: GitHub MCP, tool/skill integration
Use case: Custom tool registry, private skills, local development
Files: action.yml, src/mcp.ts, src/main.ts, documentation