feat(captain): align custom tool limits

internal/handler/api/v1/captain_custom_tool_handler.go

@@ -1,6 +1,7 @@
 package v1
 
 import (
+	"errors"
 	"net/http"
 
 	"github.com/gin-gonic/gin"
@@ -42,6 +43,10 @@ func (h *CaptainCustomToolHandler) Create(c *gin.Context) {
 	tool, err := h.svc.Create(c.Request.Context(), accountID, &req)
 	if err != nil {
 		applogger.L().Errorf("Create captain custom tool: %v", err)
+		if errors.Is(err, service.ErrCaptainCustomToolLimitExceeded) {
+			c.JSON(http.StatusUnprocessableEntity, gin.H{"error": service.ErrCaptainCustomToolLimitExceeded.Error()})
+			return
+		}
 		response.AbortWithStatusError(c, http.StatusInternalServerError, response.ErrInternal, "failed to create custom tool")
 		return
 	}