What causes "values must be an array" in wavetermdev/waveterm?

Pass values as a JSON array: {"values": [1, 2, 3]} — not a string, number, or object

values must be an array

Error message

values must be an array

What it means

The "values" key exists but its value is not a JSON array ([]any). The callback type-asserts valuesInterface.([]any) and returns this error on failure. Note an empty array is explicitly allowed (returns sum 0), so this error is strictly about the wrong type, not emptiness.

Solutions

Pass values as a JSON array: {"values": [1, 2, 3]} — not a string, number, or object
If the model keeps sending strings, strengthen the tool description with an explicit example showing an array literal
Validate client-side before invoking: check Array.isArray(values) / reflect.Kind Slice before calling the tool

Example fix

// before
anySum({"values": "1,2,3"})
// after
anySum({"values": [1, 2, 3]})

Defensive patterns

Strategy: type-guard

Validate before calling

raw, ok := m["values"]; if !ok { return errors.New("values required") }; if _, ok := raw.([]any); !ok { return errors.New("values must be a JSON array") }

Type guard

func isAnySlice(v any) ([]any, bool) { s, ok := v.([]any); return s, ok }

Try / catch

out, err := tool.Call(input); if err != nil && strings.Contains(err.Error(), "values must be an array") { return fmt.Errorf("bad tool args: %w", err) }

Prevention

Never quote the array or pass a single scalar; always [1,2,3]
Include an array example in the tool description for the model
Coerce strings like "1,2,3" into arrays before calling

When it happens

Trigger: Tool called with values as a non-array: e.g. {"values": 5}, {"values": "1,2,3"}, {"values": {"0":1}}, or null.

Common situations: Model passing a comma-separated string instead of an array; passing a single number instead of a one-element array; passing an object keyed by indices; client SDK serializing variadic args as scalars.

Related errors

AI-assisted analysis of wavetermdev/waveterm@a4447c1563 (2026-09-01). Data as JSON: /api/errors/e4297eb398e9dcdd. Report an issue: GitHub.

Appendix: source

Thrown at pkg/aiusechat/tools.go:299

				},
			},
			"required":             []string{"values"},
			"additionalProperties": false,
		},
		ToolAnyCallback: func(input any, toolUseData *uctypes.UIMessageDataToolUse) (any, error) {
			inputMap, ok := input.(map[string]any)
			if !ok {
				return nil, fmt.Errorf("invalid input format")
			}

			valuesInterface, ok := inputMap["values"]
			if !ok {
				return nil, fmt.Errorf("missing values parameter")
			}

			valuesSlice, ok := valuesInterface.([]any)
			if !ok {
				return nil, fmt.Errorf("values must be an array")
			}

			if len(valuesSlice) == 0 {
				return 0, nil
			}

			sum := 0
			for i, val := range valuesSlice {
				floatVal, ok := val.(float64)
				if !ok {
					return nil, fmt.Errorf("value at index %d is not a number", i)
				}
				sum += int(floatVal)
			}

			return sum, nil
		},
	}

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