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 falkordb-listgraphs tool checks that `cfg.Description` is set; a description is required for every tool because it is published in the tool manifest consumed by LLM clients. An empty description aborts Initialize with this error.
Source
Thrown at internal/tools/falkordb/falkordblistgraphs/falkordblistgraphs.go:67
}
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)
}
params := parameters.Parameters{}
return Tool{
BaseTool: tools.NewBaseTool(
cfg,
tools.GetAnnotationsOrDefault(cfg.Annotations, tools.NewReadOnlyAnnotations),
tools.Manifest{Description: cfg.Description, Parameters: params.Manifest(), AuthRequired: cfg.AuthRequired},
params,
),
}, nil
}
// validate interface
var _ tools.Tool = Tool{}
type Tool struct {View on GitHub (pinned to 8cc6e09de2)
Solutions
- Add a non-empty `description` field to the falkordb-listgraphs tool
- Verify indentation places description inside the tool mapping
- Regenerate or hand-write the description and reload the config
- Confirm via the toolbox tool list that the error is gone
Example fix
// before (tools.yaml)
tools:
list-graphs:
kind: falkordb-listgraphs
source: falkordb
// after
tools:
list-graphs:
kind: falkordb-listgraphs
source: falkordb
description: Lists all graphs available in the FalkorDB database. Defensive patterns
Strategy: validation
Validate before calling
if t.Description == "" {
return fmt.Errorf("tool %q (falkordb-listgraphs) requires a description", t.Name)
} Type guard
func hasNonEmptyDesc(t ToolEntry) bool { return len(strings.TrimSpace(t.Description)) > 0 } Try / catch
if _, err := cfg.Initialize(ctx); err != nil {
if strings.Contains(err.Error(), "description is required") {
return fmt.Errorf("missing description; see tool named in error: %w", err)
}
return err
} Prevention
- Never omit description even for parameterless tools like listgraphs
- Enforce tool.description presence with a JSON/YAML schema check in CI
- Document required fields in your internal tools.yaml template
- Initialize all tools in a unit test to fail fast on missing metadata
When it happens
Trigger: A `falkordb-listgraphs` tool entry in tools.yaml with the `description` field absent or empty.
Common situations: Adding a no-parameter tool and assuming description is optional for simple tools; scaffolding tools quickly in CI and filling descriptions later; YAML anchors that resolve to empty strings.
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
- error parsing argument: %w
AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05).
Data as JSON: /api/errors/fca0103159e92a22.
Report an issue: GitHub.