googleapis/mcp-toolbox · error

invalid source for %q tool: source %q is not a compatible ty

Error message

invalid source for %q tool: source %q is not a compatible type

What it means

Identical guard to the copy-object tool: cloud-storage-createbucket.ValidateSource asserts the bound source implements compatibleSource (a Cloud Storage source). Any other source kind produces this error naming the tool type and the source name.

Source

Thrown at internal/tools/cloudstorage/cloudstoragecreatebucket/cloudstoragecreatebucket.go:117

var _ tools.Tool = Tool{}

type Tool struct {
	tools.BaseTool[Config]
}

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

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

func (t Tool) ValidateSource(source sources.Source) error {
	_, ok := source.(compatibleSource)
	if !ok {
		return fmt.Errorf("invalid source for %q tool: source %q is not a compatible type", t.Cfg.Type, t.Cfg.Source)
	}
	return nil
}

func (t Tool) Invoke(ctx context.Context, s sources.Source, params parameters.ParamValues, accessToken tools.AccessToken) (any, util.ToolboxError) {
	source, ok := s.(compatibleSource)
	if !ok {
		return nil, util.NewClientServerError("source used is not compatible with the tool", http.StatusInternalServerError, nil)
	}
	mapParams := params.AsMap()
	bucket, ok := mapParams[bucketKey].(string)
	if !ok || bucket == "" {
		return nil, util.NewAgentError(fmt.Sprintf("invalid or missing '%s' parameter; expected a non-empty string", bucketKey), nil)
	}
	project := cloudstoragecommon.ResolveString(t.Cfg.Project, mapParams, projectKey)
	location := cloudstoragecommon.ResolveString(t.Cfg.Location, mapParams, locationKey)
	uniformBucketLevelAccess := cloudstoragecommon.ResolveBool(t.Cfg.UniformBucketLevelAccess, mapParams, uniformBucketLevelAccessKey)

View on GitHub (pinned to 8cc6e09de2)

Solutions

1. Set the tool's `source:` to a `kind: cloud-storage` source
2. Verify sources.yaml declares the referenced source with the Cloud Storage kind
3. Fix any renamed source references left over from refactoring

Example fix

// before
tools:
  create_bucket:
    source: mysql-src
// after
tools:
  create_bucket:
    source: gcs-src

func sourceIsGCSForCreate(s sources.Source) bool {
    _, ok := s.(cloudstoragecreatebucket.CompatibleSource)
    return ok
}
// before wiring: if !sourceIsGCSForCreate(src) { return errors.New("create_bucket requires a cloud-storage source") }

func asCompatibleCreateSource(s sources.Source) (compatibleSource, bool) {
    cs, ok := s.(compatibleSource)
    return cs, ok
}

if err := tool.ValidateSource(src); err != nil {
    return fmt.Errorf("bind create_bucket to a kind: cloud-storage source: %w", err)
}

When it happens

Trigger: A create_bucket tool entry in tools.yaml whose `source:` references a non-GCS source; passing an incompatible source instance when registering tools programmatically.

Common situations: Miswired tools.yaml after refactoring source names; reusing a generic tool template pointing at the wrong source; mixing prebuilt configs for different backends.

Related errors

• invalid source for %q tool: source %q is not a compatible ty
• description is required for tool %q
• source_bucket cannot be empty for tool %q
• destination_bucket cannot be empty 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/2ce87ecd5d2ad426. Report an issue: GitHub.