googleapis/mcp-toolbox · error

filter field cannot be empty

Error message

filter field cannot be empty

What it means

Filter-validation guard in FilterConfig.Validate: a filter object from the filters parameter parsed successfully but its `field` member is missing or empty, so there is nothing to filter on.

Source

Thrown at internal/tools/firestore/firestorequerycollection/firestorequerycollection.go:209

// validate interface
var _ tools.Tool = Tool{}

// Tool represents the Firestore query collection tool
type Tool struct {
	tools.BaseTool[Config]
}

// FilterConfig represents a filter for the query
type FilterConfig struct {
	Field string      `json:"field"`
	Op    string      `json:"op"`
	Value interface{} `json:"value"`
}

// Validate checks if the filter configuration is valid
func (f *FilterConfig) Validate() error {
	if f.Field == "" {
		return fmt.Errorf("filter field cannot be empty")
	}

	if !validOperators[f.Op] {
		ops := make([]string, 0, len(validOperators))
		for op := range validOperators {
			ops = append(ops, op)
		}
		return fmt.Errorf(errInvalidOperator, f.Op, ops)
	}

	if f.Value == nil {
		return fmt.Errorf(errMissingFilterValue, f.Field)
	}

	return nil
}

// OrderByConfig represents ordering configuration

View on GitHub (pinned to 8cc6e09de2)

Solutions

1. Include a non-empty `field` in every filter JSON object
2. Remove malformed filter entries from the filters array

When it happens

Trigger: Thrown at internal/tools/firestore/firestorequerycollection/firestorequerycollection.go:209 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/4554a6b0ac5af042. Report an issue: GitHub.