diff --git a/packages/ai/src/protocols/anthropic-messages.ts b/packages/ai/src/protocols/anthropic-messages.ts
index 2584a473afc..fd46b61118b 100644
--- a/packages/ai/src/protocols/anthropic-messages.ts
+++ b/packages/ai/src/protocols/anthropic-messages.ts
@@ -422,57 +422,74 @@ const AnthropicUsage = Schema.StructWithRest(
 )
 type AnthropicUsage = Schema.Schema.Type<typeof AnthropicUsage>
 
-const AnthropicStreamBlock = Schema.Struct({
-  type: Schema.String,
-  id: Schema.optional(Schema.String),
-  name: Schema.optional(Schema.String),
-  text: Schema.optional(Schema.String),
-  thinking: Schema.optional(Schema.String),
-  signature: Schema.optional(Schema.String),
-  // redacted_thinking blocks arrive whole in content_block_start with the
-  // encrypted payload in `data`; there is no streaming delta sequence.
-  data: Schema.optional(Schema.String),
-  input: Schema.optional(Schema.Unknown),
-  // *_tool_result blocks arrive whole as content_block_start (no streaming
-  // delta) with the structured payload in `content` and the originating
-  // server_tool_use id in `tool_use_id`.
-  tool_use_id: Schema.optional(Schema.String),
-  content: Schema.optional(Schema.Unknown),
-})
+const AnthropicStreamBlock = Schema.StructWithRest(
+  Schema.Struct({
+    type: Schema.String,
+    id: Schema.optional(Schema.String),
+    name: Schema.optional(Schema.String),
+    text: Schema.optional(Schema.String),
+    thinking: Schema.optional(Schema.String),
+    signature: Schema.optional(Schema.String),
+    // redacted_thinking blocks arrive whole in content_block_start with the
+    // encrypted payload in `data`; there is no streaming delta sequence.
+    data: Schema.optional(Schema.String),
+    input: Schema.optional(Schema.Unknown),
+    // *_tool_result blocks arrive whole as content_block_start (no streaming
+    // delta) with the structured payload in `content` and the originating
+    // server_tool_use id in `tool_use_id`.
+    tool_use_id: Schema.optional(Schema.String),
+    content: Schema.optional(Schema.Unknown),
+  }),
+  [JsonObject],
+)
 type AnthropicStreamBlock = Schema.Schema.Type<typeof AnthropicStreamBlock>
 const decodeAnthropicStreamBlock = Schema.decodeUnknownOption(AnthropicStreamBlock)
 
-const AnthropicStreamDelta = Schema.Struct({
-  content: optionalNull(Schema.String),
-  type: Schema.optional(Schema.String),
-  text: Schema.optional(Schema.String),
-  thinking: Schema.optional(Schema.String),
-  partial_json: Schema.optional(Schema.String),
-  signature: Schema.optional(Schema.String),
-  stop_reason: optionalNull(Schema.String),
-  stop_sequence: optionalNull(Schema.String),
-  stop_details: optionalNull(
-    Schema.Struct({ category: optionalNull(Schema.String), explanation: optionalNull(Schema.String) }),
-  ),
-})
+const AnthropicStreamDelta = Schema.StructWithRest(
+  Schema.Struct({
+    content: optionalNull(Schema.String),
+    type: Schema.optional(Schema.String),
+    text: Schema.optional(Schema.String),
+    thinking: Schema.optional(Schema.String),
+    partial_json: Schema.optional(Schema.String),
+    signature: Schema.optional(Schema.String),
+    stop_reason: optionalNull(Schema.String),
+    stop_sequence: optionalNull(Schema.String),
+    stop_details: optionalNull(
+      Schema.StructWithRest(
+        Schema.Struct({ category: optionalNull(Schema.String), explanation: optionalNull(Schema.String) }),
+        [JsonObject],
+      ),
+    ),
+  }),
+  [JsonObject],
+)
 type AnthropicStreamDelta = Schema.Schema.Type<typeof AnthropicStreamDelta>
 const decodeAnthropicStreamDelta = Schema.decodeUnknownOption(AnthropicStreamDelta)
 
-const AnthropicEvent = Schema.Struct({
-  type: Schema.String,
-  index: Schema.optional(Schema.Number),
-  message: Schema.optional(Schema.Struct({ usage: Schema.optional(AnthropicUsage) })),
-  content_block: Schema.optional(Schema.Unknown),
-  delta: Schema.optional(Schema.Unknown),
-  usage: Schema.optional(AnthropicUsage),
-  // `type` and `message` are both required per Anthropic's spec, but
-  // OpenAI-compatible proxies and gateway translations occasionally drop one
-  // or the other; mark them optional so a partial payload still parses and
-  // the parser can fall back to whichever field is populated.
-  error: Schema.optional(
-    Schema.Struct({ type: Schema.optional(Schema.String), message: Schema.optional(Schema.String) }),
-  ),
-})
+const AnthropicEvent = Schema.StructWithRest(
+  Schema.Struct({
+    type: Schema.String,
+    index: Schema.optional(Schema.Number),
+    message: Schema.optional(
+      Schema.StructWithRest(Schema.Struct({ usage: Schema.optional(AnthropicUsage) }), [JsonObject]),
+    ),
+    content_block: Schema.optional(Schema.Unknown),
+    delta: Schema.optional(Schema.Unknown),
+    usage: Schema.optional(AnthropicUsage),
+    // `type` and `message` are both required per Anthropic's spec, but
+    // OpenAI-compatible proxies and gateway translations occasionally drop one
+    // or the other; mark them optional so a partial payload still parses and
+    // the parser can fall back to whichever field is populated.
+    error: Schema.optional(
+      Schema.StructWithRest(
+        Schema.Struct({ type: Schema.optional(Schema.String), message: Schema.optional(Schema.String) }),
+        [JsonObject],
+      ),
+    ),
+  }),
+  [JsonObject],
+)
 type AnthropicEvent = Schema.Schema.Type<typeof AnthropicEvent>
 
 interface ParserState {
diff --git a/packages/ai/src/protocols/open-responses.ts b/packages/ai/src/protocols/open-responses.ts
index 0e3f1e60006..1672f4b7ce6 100644
--- a/packages/ai/src/protocols/open-responses.ts
+++ b/packages/ai/src/protocols/open-responses.ts
@@ -301,18 +301,26 @@ export const OpenResponsesBody = Schema.Struct({
 })
 export type OpenResponsesBody = Schema.Schema.Type<typeof OpenResponsesBody>
 
-export const OpenResponsesUsage = Schema.Struct({
-  input_tokens: Schema.optional(Schema.Number),
-  input_tokens_details: optionalNull(
-    Schema.Struct({
-      cached_tokens: Schema.optional(Schema.Number),
-      cache_write_tokens: Schema.optional(Schema.Number),
-    }),
-  ),
-  output_tokens: Schema.optional(Schema.Number),
-  output_tokens_details: optionalNull(Schema.Struct({ reasoning_tokens: Schema.optional(Schema.Number) })),
-  total_tokens: Schema.optional(Schema.Number),
-})
+export const OpenResponsesUsage = Schema.StructWithRest(
+  Schema.Struct({
+    input_tokens: Schema.optional(Schema.Number),
+    input_tokens_details: optionalNull(
+      Schema.StructWithRest(
+        Schema.Struct({
+          cached_tokens: Schema.optional(Schema.Number),
+          cache_write_tokens: Schema.optional(Schema.Number),
+        }),
+        [JsonObject],
+      ),
+    ),
+    output_tokens: Schema.optional(Schema.Number),
+    output_tokens_details: optionalNull(
+      Schema.StructWithRest(Schema.Struct({ reasoning_tokens: Schema.optional(Schema.Number) }), [JsonObject]),
+    ),
+    total_tokens: Schema.optional(Schema.Number),
+  }),
+  [JsonObject],
+)
 type OpenResponsesUsage = Schema.Schema.Type<typeof OpenResponsesUsage>
 
 // The spec requires `id` on every output item, but some gateways drop it from