googleapis/mcp-toolbox · error

description is required for tool %q

Error message

description is required for tool %q

What it means

Config.Initialize in the snowflake-sql tool requires a non-empty description before the tool can be built. The description becomes the tool manifest shown to LLM clients; without it the tool would be unusable/undeclared, so Initialize fails fast with this error.

Source

Thrown at internal/tools/snowflake/snowflakesql/snowflakesql.go:70

	tools.ConfigBase   `yaml:",inline"`
	Type               string                 `yaml:"type" validate:"required"`
	Source             string                 `yaml:"source" validate:"required"`
	Statement          string                 `yaml:"statement" validate:"required"`
	Parameters         parameters.Parameters  `yaml:"parameters"`
	TemplateParameters parameters.Parameters  `yaml:"templateParameters"`
	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)
	}

	allParameters, paramManifest, err := parameters.ProcessParameters(cfg.TemplateParameters, cfg.Parameters)
	if err != nil {
		return nil, err
	}

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

// validate interface

View on GitHub (pinned to 8cc6e09de2)

Solutions

1. Add a `description:` field to the snowflake-sql tool entry in your YAML config.
2. If constructing Config in Go, set ConfigBase.Description before calling Initialize.
3. Validate your YAML keys (indentation, singular `description`) — an empty string passes decoding and only fails in Initialize.

Example fix

// before (tools.yaml)
my-tool:
  kind: snowflake-sql
  source: my-snowflake-source
  statement: SELECT 1
// after
my-tool:
  kind: snowflake-sql
  source: my-snowflake-source
  description: Runs a SQL statement against Snowflake.
  statement: SELECT 1

if cfg.Description == "" {
	return fmt.Errorf("tool %q is missing required field: description", cfg.Name)
}

if err := toolInitialize(); err != nil {
	if strings.Contains(err.Error(), "description is required") {
		// add the missing description to the tool config and retry
	}
	return err
}

When it happens

Trigger: Calling Initialize on a snowflake-sql Config whose ConfigBase.Description is the empty string — typically after decoding a tools.yaml entry that omits the `description` field.

Common situations: A tools.yaml tool entry missing `description:`; programmatically constructing Config{Name: ...} without setting Description; a YAML typo like `descriptions:` that silently decodes to 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
• description is required for tool %q
• description is required for tool %q

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/17ec6f98f77b74da. Report an issue: GitHub.