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

The dataplexgetdataprofile tool's ValidateSource emits this error when `source.(compatibleSource)` fails — the supplied source does not implement the GetDataProfile method the tool needs. This guard ensures the tool never invokes a method that doesn't exist on the wired source. The error reflects a tool/source type mismatch in configuration or code, not a runtime API failure.

Source

Thrown at internal/tools/dataplex/dataplexgetdataprofile/dataplexgetdataprofile.go:99

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)
	}
	paramsMap := params.AsMap()
	scanId, _ := paramsMap["scanId"].(string)
	location, _ := paramsMap["location"].(string)

	if scanId == "" {
		return nil, util.NewAgentError("scanId parameter is required", nil)
	}
	if location == "" {
		return nil, util.NewAgentError("location parameter is required", nil)

View on GitHub (pinned to 8cc6e09de2)

Solutions

  1. Point the tool's `source` config at a Dataplex source implementing GetDataProfile.
  2. Verify interface satisfaction against compatibleSource in internal/tools/dataplex/dataplexgetdataprofile/dataplexgetdataprofile.go.
  3. Add/repair the GetDataProfile method on custom sources to match the interface.
  4. Add a compile-time assertion `var _ compatibleSource = (*mySource)(nil)` to catch drift early.

Example fix

// before
// func (s *MySource) GetDataProfile(ctx context.Context, id string) (*dataplex.DataProfileResult, error) // wrong signature
//
// after: match interface exactly
// func (s *MySource) GetDataProfile(ctx context.Context, locationId, dataAssetId string) (*dataplex.DataProfileResult, error)
Defensive patterns

Strategy: type-guard

Validate before calling

var _ interface {
	GetDataProfile(ctx context.Context, locationId, dataAssetId string) (*dataplex.DataProfileResult, error)
} = (*myDataplexSource)(nil)

Type guard

func isGetDataProfileSource(s sources.Source) bool {
	_, ok := s.(dataplexgetdataprofile.CompatibleSource)
	return ok
}

Try / catch

err := tool.ValidateSource(src)
if err != nil {
	var ve *util.ToolboxError
	if errors.As(err, &ve) {
		return nil, fmt.Errorf("reconfigure tool %q with a dataplex source", toolName)
	}
	return nil, err
}

Prevention

When it happens

Trigger: Calling ValidateSource with a non-Dataplex source, a Dataplex source lacking GetDataProfile(ctx, locationId, dataAssetId), or a test double that only implements sources.Source.

Common situations: Wrong source referenced in the tool's YAML block; custom or legacy source implementations missing the profile-lookup method; method signature changes during refactors breaking interface satisfaction; mixing tool definitions from different releases.

Related errors

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/143681fe24457bb7. Report an issue: GitHub.