additional-properties-false
Category: Structural — overall schema structure triggers this rule
Error Codes
| Profile | Code | Severity |
|---|---|---|
| openai.so.2026-04-30 | OAI-S-additional-properties-false | Forbid |
| anthropic.so.2026-04-30 | ANT-S-additional-properties-false | Forbid |
Description
Every object schema must declare additionalProperties: false
Provider Evidence
| Profile | Status | Source | Basis |
|---|---|---|---|
| anthropic.so.2026-04-30 | documented | Anthropic JSON Schema limitations | — |
| openai.so.2026-04-30 | documented | OpenAI additionalProperties | — |
Rationale
Providers require object nodes to explicitly reject extra properties.
Bad Example
{ "type": "object", "properties": { "name": { "type": "string" } } }
Good Example
{ "type": "object", "additionalProperties": false, "properties": { "name": { "type": "string" } } }