googleapis/mcp-toolbox · error

description is required for tool %q

Error message

description is required for tool %q

What it means

cloudhealthcarefhirfetchpage.Config.Initialize requires a non-empty description before building the tool; this tool does not supply a default description, so the user must provide one in tools.yaml. Failure aborts tool creation with the tool's name in the message.

Source

Thrown at internal/tools/cloudhealthcare/cloudhealthcarefhirfetchpage/cloudhealthcarefhirfetchpage.go:69

}

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)
	}

	urlParameter := parameters.NewStringParameter(pageURLKey, "The full URL of the FHIR page to fetch. This would be the value of `Bundle.entry.link.url` field within the response returned from FHIR search or FHIR patient everything operations.")
	allParameters := parameters.Parameters{urlParameter}

	return Tool{
		BaseTool: tools.NewBaseTool(
			cfg,
			tools.GetAnnotationsOrDefault(cfg.Annotations, tools.NewReadOnlyAnnotations),
			tools.Manifest{Description: cfg.Description, Parameters: allParameters.Manifest(), AuthRequired: cfg.AuthRequired},
			allParameters,
		),
	}, nil
}

// validate interface
var _ tools.Tool = Tool{}

View on GitHub (pinned to 8cc6e09de2)

Solutions

1. Add a non-empty description to the tool's yaml block
2. Verify exact key spelling 'description' with no empty anchors
3. Re-run the server to confirm the tool loads

Example fix

// before
  fetch-page:
    kind: cloud-healthcare-fhir-fetch-page
    source: fhir-src
// after
  fetch-page:
    kind: cloud-healthcare-fhir-fetch-page
    source: fhir-src
    description: "Fetch a page of FHIR resources using a bundle link URL"

func checkDescription(cfg map[string]any) error {
	d, _ := cfg["description"].(string)
	if d == "" { return errors.New("description is required") }
	return nil
}

When it happens

Trigger: A cloud-healthcare-fhir-fetch-page tool entry in tools.yaml missing the description field or with description: "".

Common situations: Minimal config examples copied without the description line; templates/anchors leaving the field empty; misspelled key so the struct field stays empty.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• description is required for tool %q
• description is required for tool %q
• description is required for tool %q
• doc %d: unexpected non-string key in input: %v
• doc %d: invalid config format at key %q: %w

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/1e48d1836157a0de. Report an issue: GitHub.