Cannot create a pull request and assign it to Copilot Coding Agent with certain token types

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Describe the bug
I am using the MCP server to create a pull request and assign it to the Copilot Coding Agent. When using a GitHub App installation token, it returns a 401 unauthorized. When using a PAT (fine-grained) from my personal account, it also returns a 401 unauthorized. When using a PAT (classic), it does work.

Steps to reproduce the behavior
Generate an installation token for a GitHub app or PAT (fine-grained) for a personal account
Ask Copilot to create a pull request and assign it to Copilot via the Remote MCP

Expected vs actual behavior

Expected: Pull Request is created
Actual: 401 Unauthorized received