What causes "error creating request: %w" in googleapis/mcp-toolbox?

Fix the baseUrl in the Dgraph source config to a full absolute URL including scheme, e.g. http://dgraph:8080.

error creating request: %w

Error message

error creating request: %w

What it means

Thrown by the Dgraph source's healthCheck when http.NewRequest fails to construct the GET /health request (typically an invalid URL produced by getUrl from the configured baseUrl). The underlying parse/construct error is wrapped with %w. It indicates the source's baseUrl configuration is malformed rather than that Dgraph is unreachable.

Source

Thrown at internal/sources/dgraph/dgraph.go:349

		return fmt.Errorf("no access JWT found in the response")
	}
	if r.Data.RefreshJWT == "" {
		return fmt.Errorf("no refresh JWT found in the response")
	}

	hc.AccessJwt = r.Data.AccessJWT
	hc.RefreshToken = r.Data.RefreshJWT
	return nil
}

func (hc *DgraphClient) healthCheck() error {
	url, err := getUrl(hc.baseUrl, "/health", nil)
	if err != nil {
		return err
	}
	req, err := http.NewRequest(http.MethodGet, url, nil)
	if err != nil {
		return fmt.Errorf("error creating request: %w", err)
	}

	resp, err := hc.httpClient.Do(req)
	if err != nil {
		return fmt.Errorf("error performing request: %w", err)
	}

	defer resp.Body.Close()
	data, err := io.ReadAll(resp.Body)
	if err != nil {
		return err
	}
	var result []struct {
		Instance string `json:"instance"`
		Address  string `json:"address"`
		Status   string `json:"status"`
	}

View on GitHub (pinned to 8cc6e09de2)

Solutions

Fix the baseUrl in the Dgraph source config to a full absolute URL including scheme, e.g. http://dgraph:8080.
Test the URL locally with curl to confirm it parses, e.g. curl http://dgraph:8080/health.
Check for stray whitespace or quotes around the value in the YAML/tool config file.

Example fix

// before
baseUrl: dgraph:8080
// after
baseUrl: http://dgraph:8080

Defensive patterns

Strategy: validation

Validate before calling

u, err := url.ParseRequestURI(cfg.Address)
if err != nil || u.Scheme == "" || u.Host == "" {
    return fmt.Errorf("invalid dgraph baseUrl %q: must be an absolute URL like http://host:8080", cfg.Address)
}

Try / catch

if err := healthCheck(ctx); err != nil {
    if strings.Contains(err.Error(), "error creating request") {
        // treat as configuration error: fail fast, do not retry
        return fmt.Errorf("misconfigured dgraph baseUrl: %w", err)
    }
    return err
}

Prevention

Always store the Dgraph address as a full absolute URL including http:// scheme and HTTP port (8080), not the gRPC port (9080).
Validate the source config with a URL parse check before deploying.
Avoid hand-edited URLs with stray whitespace or quotes in YAML.

When it happens

Trigger: healthCheck is invoked (periodically or on connection use) and http.NewRequest(http.MethodGet, url, nil) returns an error because the url string built from hc.baseUrl plus "/health" cannot be parsed as a valid HTTP request target.

Common situations: BaseUrl set to something like "dgraph:8080" without a scheme, containing spaces or control characters, or an empty/placeholder value left in the YAML config.

Related errors

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/0d91863739c99092. Report an issue: GitHub.