googleapis/mcp-toolbox · error

description is required for tool %q

Error message

description is required for tool %q

What it means

Configuration-time validation in Initialize: the elasticsearch-esql tool entry omits its description; Toolbox refuses to construct the tool because the manifest shown to the LLM would be incomplete.

Source

Thrown at internal/tools/elasticsearch/elasticsearchesql/elasticsearchesql.go:78

}

func newConfig(ctx context.Context, name string, decoder *yaml.Decoder) (tools.ToolConfig, error) {
	actual := Config{ConfigBase: tools.ConfigBase{Name: name}}
	if err := decoder.DecodeContext(ctx, &actual); err != nil {
		return nil, err
	}
	return actual, nil
}

type Tool struct {
	tools.BaseTool[Config]
}

var _ tools.Tool = Tool{}

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

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

func (t Tool) GetSourceName() string {
	return t.Cfg.Source
}

func (t Tool) ToConfig() tools.ToolConfig {
	return t.Cfg

View on GitHub (pinned to 8cc6e09de2)

Solutions

1. Add a non-empty description to the tool entry in tools.yaml
2. Check YAML indentation so description parses as a string rather than null

When it happens

Trigger: Thrown at internal/tools/elasticsearch/elasticsearchesql/elasticsearchesql.go:78 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/fd2d3172a84e0713. Report an issue: GitHub.