One unbilled verification of the stored secret, no row written, no status change: for a HubSpot grant it introspects the refresh token (a green answer means the grant is alive); for a custom connection it is a shape check only, since the real probe is the tool's test_custom_tool. result: ok, http_code, error_kind (none, auth, network, timeout, provider), duration_ms. Reviving a failed row is update_provider_connection.

Contract:

• MCP tool test_provider_connection, registry package mcp.integrations/provider_connections, mount integrations.providers.
• Operation action, response envelope action.
• Flags: read only.