googleapis/mcp-toolbox · error

%s: %s

Error message

%s: %s

What it means

wrapGCPProjectHint decorates errors raised while creating the GCP cloud trace/meter exporters. When the underlying error indicates Application Default Credentials could not detect a project, the error is prefixed with a hint to set --telemetry-gcp-project or GOOGLE_CLOUD_PROJECT and point GOOGLE_APPLICATION_CREDENTIALS at valid ADC credentials.

Source

Thrown at internal/telemetry/telemetry.go:203

			metric.Instrument{Name: name},
			metric.Stream{
				Aggregation: metric.AggregationExplicitBucketHistogram{
					Boundaries: durationBuckets,
				},
			},
		))
	}
	metricOpts = append(metricOpts, metric.WithView(views...))

	meterProvider := metric.NewMeterProvider(metricOpts...)
	return meterProvider, nil
}

func wrapGCPProjectHint(err error) error {
	message := err.Error()
	if strings.Contains(message, "no project found with application default credentials") {
		projectHint := "please ensure that `--telemetry-gcp-project` flag or `GOOGLE_CLOUD_PROJECT` env var is set, and `GOOGLE_APPLICATION_CREDENTIALS` points to valid ADC credentials"
		return fmt.Errorf("%s: %s", projectHint, message)
	}
	return err
}

View on GitHub (pinned to 8cc6e09de2)

Solutions

1. Set the --telemetry-gcp-project flag or the GOOGLE_CLOUD_PROJECT env var
2. Point GOOGLE_APPLICATION_CREDENTIALS at a valid ADC credentials file containing project_id
3. Run `gcloud auth application-default login` to establish ADC locally
4. If GCP telemetry is unintended, switch the --telemetry output to a non-GCP exporter

Example fix

// before
export GOOGLE_APPLICATION_CREDENTIALS=/path/key.json
// after
export GOOGLE_APPLICATION_CREDENTIALS=/path/key.json
export GOOGLE_CLOUD_PROJECT=my-gcp-project

if os.Getenv("GOOGLE_CLOUD_PROJECT") == "" && !flagSet("telemetry-gcp-project") &&
  os.Getenv("GOOGLE_APPLICATION_CREDENTIALS") == "" {
  log.Fatal("GCP telemetry requires GOOGLE_CLOUD_PROJECT (or --telemetry-gcp-project) and valid ADC credentials")
}

if err := telemetry.SetupOTel(...); err != nil {
  if strings.Contains(err.Error(), "no project found with application default credentials") {
    log.Fatalf("GCP project hint: %v", err)
  }
  return err
}

When it happens

Trigger: Starting the server with GCP telemetry (newTracerProvider/newMeterProvider using cloud trace or monitoring exporters) when ADC finds no project: no --telemetry-gcp-project flag, no GOOGLE_CLOUD_PROJECT env var, and credentials without a project_id.

Common situations: Local/on-prem deployments with GCP telemetry configured; service-account key files missing project_id; GOOGLE_APPLICATION_CREDENTIALS lost after a container rebuild; workload identity not attached.

Related errors

• unable to get AlloyDB connection config: %w
• error creating client from ADC: %w
• failed to find default Google Cloud credentials: %w
• unable to create client: %w
• unable to create instance admin client: %w

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/2f6d257ef6dcffbd. Report an issue: GitHub.