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

ValidateSource for the alloydb-alloydbcreatecluster tool asserts the injected sources.Source implements the tool's compatibleSource interface (an AlloyDB admin source with UseClientAuthorization and GetDefaultProject). A source of any other kind fails the assertion and this error is returned, blocking the tool from running against an incompatible source.

Source

Thrown at internal/tools/alloydb/alloydbcreatecluster/alloydbcreatecluster.go:101

}

// Tool represents the create-cluster 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
}

// Invoke executes the tool's logic.
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()
	project, ok := paramsMap["project"].(string)
	if !ok || project == "" {
		return nil, util.NewAgentError("invalid or missing 'project' parameter; expected a non-empty string", nil)
	}

	location, ok := paramsMap["location"].(string)
	if !ok {

View on GitHub (pinned to 8cc6e09de2)

Solutions

1. Set the tool's `source` field to an AlloyDB admin source (kind: alloydb)
2. Verify the referenced source in the `sources:` block declares the correct kind
3. Restart the toolbox and confirm the tool registers without error

Example fix

// before
tools:
  create-cluster:
    kind: alloydb-alloydbcreatecluster
    source: my-postgres-source
// after
tools:
  create-cluster:
    kind: alloydb-alloydbcreatecluster
    source: my-alloydb-admin-source

// config sanity check before startup
src, ok := sources[toolCfg.Source]
if !ok || src.SourceType() != "alloydb" {
  return fmt.Errorf("tool %q requires an alloydb admin source, got %T", toolCfg.Name, src)
}

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

if err := tool.ValidateSource(src); err != nil {
  log.Fatalf("tool misconfigured: %v", err)
}

When it happens

Trigger: Configuring the alloydb-alloydbcreatecluster tool with a `source` entry whose kind is not the AlloyDB admin source (e.g. postgres or alloydb-postgres); assertion runs at startup validation or during tool registration.

Common situations: Copy-pasted YAML where `source:` points at a SQL source; renamed/restructured config entries; mixing alloydb-postgres and alloydb admin sources in one config.

Related errors

• invalid source for %q tool: source %q is not a compatible ty
• invalid source for %q tool: source %q is not a compatible ty
• could not marshal operation: %w
• failed to unmarshal operation bytes: %w
• unable to create pool: %w

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/fe829b527f7df359. Report an issue: GitHub.