Agents should not use the browser to work around authentication or tooling failures

## Problem

When an intended CLI or dedicated tool fails because of authentication, access, or tool availability, agents may fall back to an authenticated browser session to complete the operation. This can unexpectedly use the user's logged-in services and bypass the access boundary implied by the failed tool. Examples include failures involving Work IQ, GitHub CLI, or GitHub tools.

The browser is appropriate for visual validation, user testing, and tasks that explicitly require interaction with a web experience. It should not be used as a workaround for authentication, access, or missing-tool failures.

## Expected behavior

- If the intended CLI or dedicated tool has an authentication or access failure, stop and ask the user to fix access or the tool.
- Do not fall back to a logged-in browser session to bypass that failure.
- Continue to allow browser use when the task requires visual validation, user testing, or direct web interaction.

## Suggested prompt guidance

Add explicit wording to the browser-tool system prompt along these lines:

> Do not use the browser to work around authentication, access, or missing-tool failures, including for Work IQ and other Microsoft resources. Ask the user to fix the intended access or tool instead. Use the browser when the task requires visual validation, user testing, or direct interaction with a web experience.