The --mcp tool catalogue shipped without MCP annotations, so clients
that gate execution on hints (Codex CLI approval_policy=never) cancel
even read-only calls like browser_get_state.
Annotate the five tools whose handlers only read state:
browser_get_state, browser_get_html, browser_screenshot,
browser_list_tabs, browser_list_sessions. browser_extract_content is
deliberately excluded (dispatches the extract action with a FileSystem
handle and can write artifacts). Regression test pins the set in both
directions.
Closes#5239