Power BI Remote MCP Server: Support silent token caching to avoid login prompt on every session

[ericchansen]

The Power BI Remote MCP server (https://api.fabric.microsoft.com/v1/mcp/powerbi) triggers a browser-based Microsoft Entra login prompt every time an MCP client session starts. This is disruptive for CLI-based clients like GitHub Copilot CLI where MCP servers initialize at session start.

Current behavior

• Starting a new Copilot CLI session triggers a browser popup for Entra auth
• This happens even if the user was authenticated minutes ago in a previous session
• The login prompt appears regardless of whether the user intends to use Power BI tools in that session

Expected behavior

• First-time auth should prompt normally
• Subsequent sessions should use cached/refreshed tokens silently (similar to Azure CLI's token cache in ~/.azure/)
• The server should only re-prompt when the cached token is truly expired and cannot be refreshed

Impact

• Users who want Power BI MCP available "just in case" face auth friction on every session start
• The only workaround is removing the server from MCP config entirely, losing access to Power BI tools

Suggested approach

• Cache Entra refresh tokens locally (e.g., in ~/.powerbi-mcp/ or ~/.azure/) with appropriate TTL
• On session init, attempt silent token acquisition first; only prompt interactively if silent refresh fails
• This matches the pattern used by Azure CLI, Azure Developer CLI, and other Microsoft tools that support "login once, use many"

Environment

• MCP Client: GitHub Copilot CLI
• OS: Windows 11
• MCP config entry: {"type": "http", "url": "https://api.fabric.microsoft.com/v1/mcp/powerbi"}