googleapis/mcp-toolbox · error

fail to get map params

Error message

fail to get map params: %w

What it means

RunSQL wraps any failure from getMapParamsType (which translates the tool's declared parameter types into Bigtable SQLTypes) with this message. The root cause is virtually always error 511 — an unsupported or misspelled parameter type — so the wrapped error names the offending type. It fires before any statement is sent to Bigtable.

Solutions

1. Read the wrapped error to find the offending type name and fix the tool parameter type to boolean/string/integer/float/array
2. Fix the array parameter's items.type if the failing param is an array
3. Validate the tool config before deploying (declare only supported types for Bigtable-backed tools)

Example fix

// before (tools.yaml)
parameters:
  - name: filters
    type: object
// after
parameters:
  - name: filter_value
    type: string

for _, p := range toolParams {
	t := p.GetType()
	if t != "boolean" && t != "string" && t != "integer" && t != "float" && t != "array" {
		return fmt.Errorf("param %q type %q unsupported before calling RunSQL", p.GetName(), t)
	}
}

res, err := src.RunSQL(ctx, statement, cfgParams, paramValues)
if err != nil {
	var target *bigtableSrcErr
	if strings.Contains(err.Error(), "fail to get map params") {
		// unwrap to find the offending type in the tool config
	}
	return err
}

When it happens

Trigger: RunSQL is invoked with a `configParam` (parameters.Parameters) containing a param whose type or array items.type is not boolean/string/integer/float/array; getMapParamsType returns an error which is wrapped here.

Common situations: Tool config declares `type: number` or `type: object` for a parameter used by a Bigtable execute_sql tool; nested array item type unsupported; typo'd type in tools.yaml discovered only at query time.

Related errors

• unknow param type
• unable to bind
• can't convert fields to array of strings
• can't convert pivots to array of strings
• can't convert projectIds to array of strings

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/0b88e33f90935ee8. Report an issue: GitHub.

Appendix: source

Thrown at internal/sources/bigtable/bigtable.go:171

			}
			btParamTypes[p.GetName()] = bigtable.ArraySQLType{
				ElemType: itemType,
			}
			continue
		}
		paramType, err := getBigtableType(p.GetType())
		if err != nil {
			return nil, err
		}
		btParamTypes[p.GetName()] = paramType
	}
	return btParamTypes, nil
}

func (s *Source) RunSQL(ctx context.Context, statement string, configParam parameters.Parameters, params parameters.ParamValues) (any, error) {
	mapParamsType, err := getMapParamsType(configParam)
	if err != nil {
		return nil, fmt.Errorf("fail to get map params: %w", err)
	}

	ps, err := s.BigtableClient().PrepareStatement(
		ctx,
		statement,
		mapParamsType,
	)
	if err != nil {
		return nil, fmt.Errorf("unable to prepare statement: %w", err)
	}

	bs, err := ps.Bind(params.AsMap())
	if err != nil {
		return nil, fmt.Errorf("unable to bind: %w", err)
	}

	out := []any{}
	var rowErr error

View on GitHub (pinned to 8cc6e09de2)