The managed proxy pool's countries with free stock, gtm's own feed passed through, most free proxies first and without the counts. These are the only values a form may offer for proxy_country_code, because a connect refuses a country with no free proxy; the first row is the country to pre-fill. An empty list means the pool is dry, and only the team's own proxy (custom_proxy_config) or its own GoLogin profile (vendor_profile_id) can bring a browser then. 501 while the gtm bridge is unconfigured.

Contract:

• MCP tool list_sender_profile_linkedin_proxy_countries, registry package mcp.unibox/sender_profiles, mount unibox.sender-profiles.
• Operation action, response envelope action.
• Flags: read only.