What causes "failed to create BigQuery v2 service: %w" in googleapis/mcp-toolbox?

Inspect the wrapped error with errors.As/Unwrap to identify the exact cause.

failed to create BigQuery v2 service

Error message

failed to create BigQuery v2 service: %w

What it means

This error is thrown when the low-level BigQuery REST service (google.golang.org/api/bigquery/v2) fails to initialize via bigqueryrestapi.NewService using the same client options as the high-level client. The toolbox builds both a high-level bigquery.Client and a raw REST service; failure here means the REST layer could not be created even though the high-level client succeeded. Wrapped causes are usually option validation or transport setup failures.

Solutions

Inspect the wrapped error with errors.As/Unwrap to identify the exact cause.
Verify any custom endpoint/base-URL option is a valid BigQuery v2 API URL.
Ensure only one credential mechanism (token source or credentials) is applied consistently.
Check network/proxy access to bigquery.googleapis.com and retry if transient.

Example fix

// before
opts := []option.ClientOption{
  option.WithUserAgent(userAgent),
  option.WithTokenSource(ts),
  option.WithCredentials(cred), // conflicting credential options
}
// after
opts := []option.ClientOption{
  option.WithUserAgent(userAgent),
  option.WithTokenSource(ts), // single credential mechanism
}

Defensive patterns

Strategy: try-catch

Validate before calling

// Validate connectivity to the BigQuery v2 endpoint first
resp, err := http.Get("https://bigquery.googleapis.com/")
if err != nil {
  return fmt.Errorf("BigQuery API endpoint unreachable: %w", err)
}
resp.Body.Close()

Try / catch

// Go
client, rest, ts, err := initBigQueryConnection(ctx, cfg)
if err != nil && strings.Contains(err.Error(), "failed to create BigQuery v2 service") {
  // transient? retry once with backoff before failing startup
  time.Sleep(2 * time.Second)
  client, rest, ts, err = initBigQueryConnection(ctx, cfg)
  if err != nil {
    log.Fatalf("BigQuery v2 REST service init failed: %v — check endpoint/proxy and credential options", err)
  }
}

Prevention

Avoid mixing option.WithTokenSource and option.WithCredentials in the same options slice.
Check network/proxy access to bigquery.googleapis.com.
If using a custom endpoint, verify it is a valid BigQuery v2 API URL.
Retry service construction once on transient transport errors.

When it happens

Trigger: bigqueryrestapi.NewService(ctx, opts...) returns an error while constructing the REST client from the same opts (user agent, token source/credentials, quota project) — e.g. invalid option combination, failure resolving the API endpoint, or transport/credentials setup errors inside the google-api-go-client.

Common situations: Custom base URL / endpoint misconfiguration; proxy or firewall interfering with API endpoint resolution; incompatible or conflicting option.WithTokenSource plus option.WithCredentials values; intermittent transport errors during service construction.

Related errors

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/f38fadca13233342. Report an issue: GitHub.

Appendix: source

Thrown at internal/sources/bigquery/bigquery.go:825

	if endpoint != "" {
		opts = append(opts, option.WithEndpoint(endpoint))
	}
	if quotaProject != "" {
		opts = append(opts, option.WithQuotaProject(quotaProject))
	}

	// Initialize the high-level BigQuery client
	client, err := bigqueryapi.NewClient(ctx, project, opts...)
	if err != nil {
		return nil, nil, nil, fmt.Errorf("failed to create BigQuery client for project %q: %w", project, err)
	}
	client.Location = location

	// Initialize the low-level BigQuery REST service using the same credentials
	restService, err := bigqueryrestapi.NewService(ctx, opts...)
	if err != nil {
		return nil, nil, nil, fmt.Errorf("failed to create BigQuery v2 service: %w", err)
	}

	return client, restService, tokenSource, nil
}

// initBigQueryConnectionWithOAuthToken initialize a BigQuery client with an
// OAuth access token.
func initBigQueryConnectionWithOAuthToken(
	ctx context.Context,
	tracer trace.Tracer,
	project string,
	location string,
	quotaProject string,
	name string,
	userAgent string,
	tokenString string,
	wantRestService bool,
	endpoint string,

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