googleapis/mcp-toolbox · error

description is required for tool %q

Error message

description is required for tool %q

What it means

Config.Initialize for the lookercreatedashboardlayout tool enforces that a non-empty 'description' field is present in the tool configuration before constructing the tool. Descriptions are exposed to the LLM as the tool's usage guidance, so the library treats a missing one as an invalid configuration and aborts initialization. The configured tool name is included to locate the failing YAML entry.

Source

Thrown at internal/tools/looker/lookercreatedashboardlayout/lookercreatedashboardlayout.go:71

}

type Config struct {
	tools.ConfigBase `yaml:",inline"`
	Type             string                 `yaml:"type" validate:"required"`
	Source           string                 `yaml:"source" validate:"required"`
	Annotations      *tools.ToolAnnotations `yaml:"annotations,omitempty"`
}

// validate interface
var _ tools.ToolConfig = Config{}

func (cfg Config) ToolConfigType() string {
	return resourceType
}

func (cfg Config) Initialize(context.Context) (tools.Tool, error) {
	if cfg.Description == "" {
		return nil, fmt.Errorf("description is required for tool %q", cfg.Name)
	}

	dashboardIdParam := parameters.NewStringParameter("dashboard_id", "The ID of the dashboard to create the layout for.")
	labelParam := parameters.NewStringParameter("label", "The label (title) of the layout/tab.")
	typeParam := parameters.NewStringParameter("type", "The type of layout (e.g. 'newspaper', 'grid'). Defaults to 'newspaper'.", parameters.WithStringDefault("newspaper"))
	activeParam := parameters.NewBooleanParameter("active", "Whether this layout should be active.", parameters.WithBooleanDefault(false))

	params := parameters.Parameters{
		dashboardIdParam,
		labelParam,
		typeParam,
		activeParam,
	}

	return Tool{
		BaseTool: tools.NewBaseTool(
			cfg,
			tools.GetAnnotationsOrDefault(cfg.Annotations, tools.NewWriteAnnotations),

View on GitHub (pinned to 8cc6e09de2)

Solutions

1. Add a non-empty 'description' to the looker-create-dashboard-layout tool definition.
2. Fix templating/rendering so the description is never interpolated to an empty string.
3. Restart the toolbox and confirm the tool initializes cleanly.

Example fix

# before
tools:
  create_layout:
    kind: looker-create-dashboard-layout
    source: my-looker-instance
# after
tools:
  create_layout:
    kind: looker-create-dashboard-layout
    source: my-looker-instance
    description: Creates a new layout/tab for an existing Looker dashboard.

// Go: pre-flight required fields for this tool kind
type toolCfg struct { Kind, Description string }
func validateDashboardLayoutCfg(c toolCfg) error {
    if c.Kind == "looker-create-dashboard-layout" && strings.TrimSpace(c.Description) == "" {
        return fmt.Errorf("%s requires a non-empty description", c.Kind)
    }
    return nil
}

if err := toolbox.LoadConfig(ctx, cfgPath); err != nil {
    if strings.Contains(err.Error(), "description is required for tool") {
        log.Fatalf("add 'description' to the looker-create-dashboard-layout tool: %v", err)
    }
    return err
}

When it happens

Trigger: Starting or reloading the toolbox with a looker-create-dashboard-layout tool entry whose 'description' field is absent or empty.

Common situations: Omitting the description when hand-writing tools.yaml; config templating that renders an empty value; migrating tools between kinds without re-checking required fields.

Understand the failure class

Background: "is required", "must be set", "missing required field": configuration validation errors across open-source libraries — this error's family across 36 libraries.

Related errors

• description is required for tool %q
• description is required for tool %q
• error parsing argument: %w
• invalid role %q: must be 'user' or 'assistant'
• description is required for tool %q

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/2f28dfdd2324b58f. Report an issue: GitHub.