Output schema node with only a description: missing_type violation

A property such as "notes": { "description": "anything the run wants to say" } is valid JSON Schema, where it means "any value". Sume rejects it with 400 output_schema_invalid and the rule missing_type. Every node needs a type, a $ref or an anyOf, and an array also needs items (Structured output).

The reason is the same as for the rest of the strict subset. Sume only fills a schema it can mechanically satisfy, and "anything" gives it nothing to satisfy.

The fix

Pick the real type. If the value can be absent, use a nullable union, because every declared property must also appear in required.

// rejected: missing_type at #/properties/notes
"notes": { "description": "anything the run wants to say" }

// accepted
"notes": { "type": ["string", "null"], "description": "Free text, or null." }

Where constraints go when you use $ref or anyOf

$ref and anyOf each short-circuit the node that contains them. Sume checks the sibling keywords next to them against the allowlist, but they have no other effect. If you write { "$ref": "#/$defs/scene", "minItems": 1 }, the sibling does nothing useful. Put constraints inside the anyOf branches or inside the $defs entry.

• Annotations (title, description, default, examples, $schema, $id) are accepted next to a type and do not replace one.
• strict: false does not relax any rule. Sume accepts and stores it but still rejects the schema.
• There is no JSON-mode escape hatch. You bind a schema, or you take the built-in sume/action-run-output/v1 shape.

Check before you pay

Because the rejection happens at submit, you can test a schema with the cheapest request you have and read details.violations[]. Nothing runs and nothing is charged. Log the rule and path of each entry rather than the message, since the message wording can change.