diff --git a/cmd/toolsrv/internal/server/proc.go b/cmd/toolsrv/internal/server/proc.go
index 54fa62a..68d560d 100644
--- a/cmd/toolsrv/internal/server/proc.go
+++ b/cmd/toolsrv/internal/server/proc.go
@@ -275,7 +275,14 @@ func (st *State) NewProc(ctx context.Context, payload string, background bool) (
 
 	info, ok := reg.Lookup(aid, toolName)
 	if !ok {
-		return "", 0, fmt.Errorf("tool not found: %s", toolName)
+		// Auto-load if tool exists
+		if err := reg.Load(aid, toolName); err != nil {
+			return "", 0, err // "tool not found: X"
+		}
+		info, _ = reg.Lookup(aid, toolName)
+		if st.OnToolsChanged != nil {
+			st.OnToolsChanged()
+		}
 	}
 
 	// Create proc context. For background procs, detach from request context