larksuite/cli · error

L1: outputSchema.type = %q, want "object"

Error message

L1: outputSchema.type = %q, want "object"

What it means

lintEnvelope's L1 check requires outputSchema, when present, to declare type exactly "object". The error is appended when an envelope declares a non-object output schema. This normalizes all tool outputs to JSON objects for downstream consumers.

Source

Thrown at internal/schema/lint.go:50

	// ---- L1: structural ----
	if env.Name == "" {
		errs = append(errs, errors.New("L1: name must not be empty"))
	}
	if env.InputSchema == nil {
		errs = append(errs, errors.New("L1: inputSchema must not be nil"))
	} else {
		if env.InputSchema.Type != "object" {
			errs = append(errs, fmt.Errorf("L1: inputSchema.type = %q, want \"object\"", env.InputSchema.Type))
		}
		if env.InputSchema.Properties == nil {
			errs = append(errs, errors.New("L1: inputSchema.properties must not be nil"))
		}
	}
	if env.OutputSchema == nil {
		errs = append(errs, errors.New("L1: outputSchema must not be nil"))
	} else {
		if env.OutputSchema.Type != "object" {
			errs = append(errs, fmt.Errorf("L1: outputSchema.type = %q, want \"object\"", env.OutputSchema.Type))
		}
	}
	if env.Meta == nil {
		errs = append(errs, errors.New("L1: _meta must not be nil"))
		// Cannot continue meta-dependent checks
		return errs
	}
	if env.Meta.EnvelopeVersion != "1.0" {
		errs = append(errs, fmt.Errorf("L1: _meta.envelope_version = %q, want \"1.0\"", env.Meta.EnvelopeVersion))
	}

	// L1: validate every Property type recursively
	if env.InputSchema != nil && env.InputSchema.Properties != nil {
		validatePropertyTypes(env.InputSchema.Properties, &errs)
	}
	if env.OutputSchema != nil && env.OutputSchema.Properties != nil {
		validatePropertyTypes(env.OutputSchema.Properties, &errs)
	}

View on GitHub (pinned to 7fd6ef3c07)

Solutions

1. Set outputSchema.type to "object" and nest the actual payload under properties (e.g. a data wrapper).
2. Fix typos in the type value ("objec" -> "object").
3. Re-run the lint to confirm the envelope passes L1.

Example fix

// before
"outputSchema": { "type": "array" }
// after
"outputSchema": { "type": "object", "properties": { "data": { "type": "array" } } }

func outputSchemaIsObject(env map[string]any) bool {
	s, ok := env["outputSchema"].(map[string]any)
	return ok && s["type"] == "object"
}

func hasObjectOutputSchema(env *Envelope) bool { return env.OutputSchema != nil && env.OutputSchema.Type == "object" }

errs := lintEnvelope(env)
for _, e := range errs {
	if strings.Contains(e.Error(), "outputSchema.type") {
		// fix envelope: set type "object" and wrap payloads in a data property
	}
}

When it happens

Trigger: Linting an envelope whose outputSchema.type is e.g. "string", "array", or a typo like "objec" instead of "object".

Common situations: Describing a tool that returns a list and using array as the root type instead of wrapping it in an object; hand-editing schema JSON and mistyping the type; a generator producing bare scalar output schemas.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• L1: inputSchema.type = %q, want "object"
• L1: _meta.envelope_version = %q, want "1.0"
• L2: required key %q not found in properties
• L3: _meta.danger=%v inconsistent with risk=%q
• expected boolean

AI-assisted analysis of larksuite/cli@7fd6ef3c07 (2026-09-04). Data as JSON: /api/errors/84a51b1b67226d03. Report an issue: GitHub.