googleapis/mcp-toolbox · error

failed to parse integer or float values in map: %s

Error message

failed to parse integer or float values in map: %s

What it means

For generic map parameters (no valueType declared), MapParameter.Parse runs util.ConvertNumbers to turn JSON numbers into int/float values. If any number in the map cannot be converted (e.g. out-of-range integer or a malformed numeric encoding), parsing fails with this message carrying the underlying conversion error.

Source

Thrown at internal/util/parameters/parameters.go:1346

}

// Parse validates and parses an incoming value for the map parameter.
func (p *MapParameter) Parse(v any) (any, error) {
	m, ok := v.(map[string]any)
	if !ok {
		return nil, &ParseTypeError{p.Name, p.Type, v}
	}
	if !p.IsAllowedValues(m) {
		return nil, fmt.Errorf("%s is not an allowed value", m)
	}
	if p.IsExcludedValues(m) {
		return nil, fmt.Errorf("%s is an excluded value", m)
	}
	// for generic maps, convert json.Numbers to their corresponding types
	if p.ValueType == "" {
		convertedData, err := util.ConvertNumbers(m)
		if err != nil {
			return nil, fmt.Errorf("failed to parse integer or float values in map: %s", err)
		}
		convertedMap, ok := convertedData.(map[string]any)
		if !ok {
			return nil, fmt.Errorf("internal error: ConvertNumbers should return a map, but got type %T", convertedData)
		}
		return convertedMap, nil
	}

	// Otherwise, get a prototype and parse each value in the map.
	prototype, err := getPrototypeParameter(p.ValueType)
	if err != nil {
		return nil, err
	}

	rtn := make(map[string]any, len(m))
	for key, val := range m {
		parsedVal, err := prototype.Parse(val)
		if err != nil {

View on GitHub (pinned to 8cc6e09de2)

Solutions

1. Check the wrapped inner error to find which value failed conversion.
2. Send large numbers as strings if the tool treats them as identifiers.
3. Declare an explicit valueType on the map parameter to change the conversion behavior, or fix the client-side number serialization.

Example fix

// before (number exceeds int64)
{"id": 99999999999999999999}
// after
{"id": "99999999999999999999"}

function safeNumbers(m) {
  for (const [k, v] of Object.entries(m)) {
    if (typeof v === 'number' && !Number.isSafeInteger(v) && Math.abs(v) > Number.MAX_SAFE_INTEGER) {
      throw new Error(`value for '${k}' exceeds safe numeric range; send as string`);
    }
  }
}
safeNumbers(body.attrs);

function hasFiniteNumbers(m) {
  return Object.values(m).every(v => typeof v !== 'number' || Number.isFinite(v));
}

try {
  await invokeTool('my_tool', body);
} catch (e) {
  if (e.message.includes('failed to parse integer or float values in map')) {
    console.error('Fix numeric values in map payload (range/format):', e.message);
  } else throw e;
}

When it happens

Trigger: Sending a map with no declared valueType where a value is a JSON number that ConvertNumbers cannot handle — e.g. an integer exceeding int64 range, or an unexpected numeric literal in the decoded payload.

Common situations: Clients sending huge IDs as numbers instead of strings; floating point values with extreme exponents; a backend/client JSON encoder producing non-standard numeric formats.

Understand the failure class

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

Related errors

• %t is an excluded value
• unable to parse element #%d: %w
• Invalid JSON format for ${paramName}. Expected an array. ${e
• Input for ${paramName} must be a JSON array (e.g., ["a", "b"
• /api native endpoints are disabled by default. Please use th

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/a02e399b1735c855. Report an issue: GitHub.