googleapis/mcp-toolbox · error

segment cannot be '.' or '..'

Error message

segment cannot be '.' or '..'

What it means

Segment guard in validateSegment: a path segment is '.' or '..', an attempt at relative traversal that Firestore paths do not support.

Source

Thrown at internal/tools/firestore/util/validator.go:118

func validateSegment(segment string, isCollection bool) error {
	segmentType := "document ID"
	if isCollection {
		segmentType = "collection ID"
	}

	// Check for empty segment
	if segment == "" {
		return fmt.Errorf("segment cannot be empty")
	}

	// Check for whitespace-only segment
	if strings.TrimSpace(segment) == "" {
		return fmt.Errorf("segment cannot be only whitespace")
	}

	// Check for single or double period
	if segment == "." || segment == ".." {
		return fmt.Errorf("segment cannot be '.' or '..'")
	}

	// Check for reserved prefix
	if strings.HasPrefix(segment, "__") {
		return fmt.Errorf("%s cannot start with '__' (reserved prefix)", segmentType)
	}

	return nil
}

// IsAbsolutePath checks if a path is an absolute Firestore path
func IsAbsolutePath(path string) bool {
	return absolutePathRegex.MatchString(path)
}

// IsRelativePath checks if a path is a relative Firestore path
func IsRelativePath(path string) bool {
	return path != "" && !IsAbsolutePath(path)

View on GitHub (pinned to 8cc6e09de2)

Solutions

1. Write out the literal path without dot segments
2. Use the exact collection IDs and document IDs in the path

When it happens

Trigger: Thrown at internal/tools/firestore/util/validator.go:118 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/99ed40e47e12dda4. Report an issue: GitHub.