googleapis/mcp-toolbox · error

error parsing URL path: %s

Error message

error parsing URL path: %s

What it means

The templated tool path must parse as a relative URL: getURL parses the rendered path with net/url.Parse and wraps any parse failure as "error parsing URL path". Failures here indicate the path (after parameter substitution) is not a valid URL reference.

Source

Thrown at internal/tools/http/http.go:200

	}
	var templatedPath bytes.Buffer
	err = templ.Execute(&templatedPath, pathParamsMap)
	if err != nil {
		return "", fmt.Errorf("error replacing pathParams: %s", err)
	}

	baseParsedURL, err := url.Parse(baseURL)
	if err != nil {
		return "", fmt.Errorf("error parsing base URL: %s", err)
	}
	if baseParsedURL.Scheme == "" || baseParsedURL.Host == "" {
		return "", fmt.Errorf("base URL must include scheme and host")
	}

	relativePath := templatedPath.String()
	relParsedURL, err := url.Parse(relativePath)
	if err != nil {
		return "", fmt.Errorf("error parsing URL path: %s", err)
	}
	if relParsedURL.Scheme != "" || relParsedURL.Host != "" || relParsedURL.User != nil {
		return "", fmt.Errorf("path must be relative and cannot override base host")
	}

	// Reject dot segments before resolution
	for _, segment := range strings.Split(relParsedURL.Path, "/") {
		if segment == ".." {
			return "", fmt.Errorf("path cannot contain dot segments (..)")
		}
	}

	// Create URL based on BaseURL and Path
	// Attach query parameters
	parsedURL := baseParsedURL.ResolveReference(relParsedURL)

	// Verify final path stays within base path scope
	basePath := baseParsedURL.Path

View on GitHub (pinned to 8cc6e09de2)

Solutions

1. Wrap path-param interpolations with the provided "pathEscape" template function, e.g. {{.id | pathEscape}}.
2. Sanitize or reject invalid characters in path param values before invocation.
3. Check the tool's static "path" for typos such as malformed percent-encodings or stray whitespace.

Example fix

// before
path: "/files/{{.name}}"
// after
path: "/files/{{.name | pathEscape}}"

// Verify rendered path parses as a relative URL before invoking
rel, err := url.Parse(renderedPath)
if err != nil {
    return fmt.Errorf("rendered path %q is not a valid URL reference: %w", renderedPath, err)
}

urlString, err := getURL(baseURL, path, pathParams, queryParams, defaultQuery, paramsMap)
if err != nil {
    if strings.HasPrefix(err.Error(), "error parsing URL path") {
        return nil, fmt.Errorf("rendered path invalid; check path param values: %w", err)
    }
    return nil, err
}

When it happens

Trigger: A rendered path containing invalid characters — e.g. raw spaces, invalid percent-escapes like "%zz", or control characters injected via an unsanitized path param — makes url.Parse of the relative path fail during Invoke.

Common situations: User/LLM-supplied path parameter values containing spaces or malformed escapes interpolated into the path without pathEscape; copy-pasted paths with trailing whitespace or invisible characters.

Understand the failure class

Background: "Invalid URL" errors: why new URL(), URI.parse, and reqwest::Url reject your string — missing scheme, whitespace, and bad path format — this error's family across 39 libraries.

Related errors

• error parsing URL: %s
• error replacing pathParams: %s
• failed to create request: %w
• error parsing base URL: %s
• base URL must include scheme and host

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/0bdf8fe75fe6860d. Report an issue: GitHub.