googleapis/mcp-toolbox · error

failed to parse filter at index %d: %w

Error message

failed to parse filter at index %d: %w

What it means

JSON-decode wrap in parseFilters: the filter string at the given index is not valid JSON, so it cannot be unmarshalled into a FilterConfig.

Source

Thrown at internal/tools/firestore/firestorequerycollection/firestorequerycollection.go:371

	filters, ok := filtersRaw.([]any)
	if !ok {
		return nil, fmt.Errorf(errInvalidFilters, filtersKey)
	}

	if len(filters) > maxFilterLength {
		return nil, fmt.Errorf(errTooManyFilters, len(filters), maxFilterLength)
	}

	result := make([]FilterConfig, 0, len(filters))
	for i, filterRaw := range filters {
		filterJSON, ok := filterRaw.(string)
		if !ok {
			return nil, fmt.Errorf(errFilterNotString, i)
		}

		var filter FilterConfig
		if err := json.Unmarshal([]byte(filterJSON), &filter); err != nil {
			return nil, fmt.Errorf(errFilterParseFailed, i, err)
		}

		if err := filter.Validate(); err != nil {
			return nil, fmt.Errorf("filter at index %d is invalid: %w", i, err)
		}

		result = append(result, filter)
	}

	return result, nil
}

// parseOrderBy parses the orderBy configuration
func (t Tool) parseOrderBy(orderByRaw interface{}) (*OrderByConfig, error) {
	orderByJSON, ok := orderByRaw.(string)
	if !ok || orderByJSON == "" {
		return nil, nil
	}

View on GitHub (pinned to 8cc6e09de2)

Solutions

1. Fix the JSON syntax of the filter string (quotes, commas, braces)
2. Validate the filter string with a JSON linter before sending

When it happens

Trigger: Thrown at internal/tools/firestore/firestorequerycollection/firestorequerycollection.go:371 when the library encounters an invalid state.

Common situations: See trigger scenarios.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/f2207516da7948e1. Report an issue: GitHub.