Constant MCP_DRAIN_TIMEOUTS_HELP 

pub const MCP_DRAIN_TIMEOUTS_HELP: &str = "Shutdown MCP-inflight drain hit its 5 s deadline before every detached \
     mcp_call_inner spawn completed. Downstream effects: some detached \
     tool bodies were interrupted at close and their sessions may be \
     quarantined at restart-time recovery. Any occurrence during a \
     rollout indicates a class of tool calls that regularly outlive HTTP \
     drain (long-running upstream tool, hung sandbox); check the \
     coincident tracing warn line.";

Shared HELP for av_shutdown_mcp_drain_timeouts_total (boot pre-registration and shutdown-path lookup in main.rs). Same first-wins/no-drift rationale as SESSION_CLOSE_TIMEOUTS_HELP.