feat(api): add support for Structured Outputs in the Messages API

Author: stainless-app[bot]

.github/workflows/claude.yml

@@ -36,6 +36,9 @@ jobs:
         with:
           anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}
 
+          # Allow github-actions[bot] to trigger Claude Code Action
+          allowed_bots: "stainless-app"
+
           # This is an optional setting that allows Claude to read CI results on PRs
           additional_permissions: |
             actions: read
@@ -47,4 +50,3 @@ jobs:
           # See https://github.com/anthropics/claude-code-action/blob/main/docs/usage.md
           # or https://code.claude.com/docs/en/cli-reference for available options
           # claude_args: '--allowed-tools Bash(gh pr:*)'
-

.stats.yml

@@ -1,4 +1,4 @@
 configured_endpoints: 34
-openapi_spec_url: https://storage.googleapis.com/stainless-sdk-openapi-specs/anthropic%2Fanthropic-f7bcdc13402c6129b30be620021a724945de44cffc6add091798f9cce33a1e32.yml
-openapi_spec_hash: e78807e31b9233abc50ccc00304bfa4d
-config_hash: 712e84f0cacb3436913f57da3d959b5c
+openapi_spec_url: https://storage.googleapis.com/stainless-sdk-openapi-specs/anthropic%2Fanthropic-4526612d12e919de063708c05d15b78902b5a52d33a6e3eb45708c562d338b18.yml
+openapi_spec_hash: 346bef71688ca79b107cf84bc09249ac
+config_hash: 0b96ef87fc0758bbc543ffa8435baa2a

api.md

@@ -45,13 +45,15 @@ from anthropic.types import (
     DocumentBlockParam,
     ImageBlockParam,
     InputJSONDelta,
+    JSONOutputFormat,
     Message,
     MessageCountTokensTool,
     MessageDeltaUsage,
     MessageParam,
     MessageTokensCount,
     Metadata,
     Model,
+    OutputConfig,
     PlainTextSource,
     RawContentBlockDelta,
     RawContentBlockDeltaEvent,

examples/structured_outputs.py

@@ -1,14 +1,3 @@
-# /// script
-# requires-python = ">=3.9"
-# dependencies = [
-#     "anthropic",
-# ]
-#
-# [tool.uv.sources]
-# anthropic = { path = "../", editable = true }
-# ///
-
-
 import pydantic
 
 import anthropic
@@ -27,7 +16,7 @@ class Order(pydantic.BaseModel):
 "Hi, I’d like to order 2 packs of Green Tea for 5.50 dollars each."
 """
 
-parsed_message = client.beta.messages.parse(
+parsed_message = client.messages.parse(
     model="claude-sonnet-4-5",
     messages=[{"role": "user", "content": prompt}],
     max_tokens=1024,

examples/structured_outputs_streaming.py

@@ -1,13 +1,3 @@
-# /// script
-# requires-python = ">=3.9"
-# dependencies = [
-#     "anthropic",
-# ]
-#
-# [tool.uv.sources]
-# anthropic = { path = "../", editable = true }
-# ///
-
 import pydantic
 
 import anthropic
@@ -23,10 +13,10 @@ class Order(pydantic.BaseModel):
 
 prompt = """
 Extract the product name, price, and quantity from this customer message:
-"Hi, I’d like to order 2 packs of Green Tea for 5.50 dollars each."
+"Hi, I'd like to order 2 packs of Green Tea for 5.50 dollars each."
 """
 
-with client.beta.messages.stream(
+with client.messages.stream(
     model="claude-sonnet-4-5",
     messages=[{"role": "user", "content": prompt}],
     max_tokens=1024,
@@ -35,3 +25,7 @@ class Order(pydantic.BaseModel):
     for event in stream:
         if event.type == "text":
             print(event.parsed_snapshot())
+
+    # Get the final parsed output
+    final_message = stream.get_final_message()
+    print(f"\nFinal parsed order: {final_message.parsed_output}")

src/anthropic/lib/_parse/_response.py

@@ -5,6 +5,8 @@
 from ..._types import NotGiven
 from ..._models import TypeAdapter, construct_type_unchecked
 from ..._utils._utils import is_given
+from ...types.message import Message
+from ...types.parsed_message import ParsedMessage, ParsedTextBlock, ParsedContentBlock
 from ...types.beta.beta_message import BetaMessage
 from ...types.beta.parsed_beta_message import ParsedBetaMessage, ParsedBetaTextBlock, ParsedBetaContentBlock
 
@@ -18,7 +20,7 @@ def parse_text(text: str, output_format: ResponseFormatT | NotGiven) -> Response
     return None
 
 
-def parse_response(
+def parse_beta_response(
     *,
     output_format: ResponseFormatT | NotGiven,
     response: BetaMessage,
@@ -42,3 +44,29 @@ def parse_response(
             "content": content_list,
         },
     )
+
+
+def parse_response(
+    *,
+    output_format: ResponseFormatT | NotGiven,
+    response: Message,
+) -> ParsedMessage[ResponseFormatT]:
+    content_list: list[ParsedContentBlock[ResponseFormatT]] = []
+    for content in response.content:
+        if content.type == "text":
+            content_list.append(
+                construct_type_unchecked(
+                    type_=ParsedTextBlock[ResponseFormatT],
+                    value={**content.to_dict(), "parsed_output": parse_text(content.text, output_format)},
+                )
+            )
+        else:
+            content_list.append(content)  # type: ignore
+
+    return construct_type_unchecked(
+        type_=ParsedMessage[ResponseFormatT],
+        value={
+            **response.to_dict(),
+            "content": content_list,
+        },
+    )

src/anthropic/lib/streaming/__init__.py

@@ -6,6 +6,9 @@
     MessageStopEvent as MessageStopEvent,
     MessageStreamEvent as MessageStreamEvent,
     ContentBlockStopEvent as ContentBlockStopEvent,
+    ParsedMessageStopEvent as ParsedMessageStopEvent,
+    ParsedMessageStreamEvent as ParsedMessageStreamEvent,
+    ParsedContentBlockStopEvent as ParsedContentBlockStopEvent,
 )
 from ._messages import (
     MessageStream as MessageStream,