GET

/v1/schemas/meta/chat/v1/messages

Accept:

kind inputactivity chathash 57cfddf4…extracted Nov 9, 2026version currentsource upstream spec ↗

field	recorded source
schema	Source linked above. docs-derived Source trace `8c415446cb01a31230c16a00fc7b79e7928c112fe28defd8f89862e13b9fefd1` { "fetchedAt": 1794201665, "extractorVersion": "2", "verifiedAt": null }

Request body

14 properties · 3 required · 45 $defs

property	type	description	constraints
model*	string	(minLength: 1)	length ≥ 1
messages*	anthropic-input-message[]	(minItems: 1)	items ≥ 1
max_tokens*	integer	(minimum: 1)	n ≥ 1
system	string \| anthropic-system-text-block-param[]
tools	anthropic-tool[]
tool_choice	anthropic-tool-choice
metadata	anthropic-metadata-param
temperature	number	(minimum: 0, maximum: 1)	nullable
top_p	number	(minimum: 0, maximum: 1)	nullable
thinking	object \| object \| object
service_tier	enum		auto \| standard_only
cache_control	anthropic-cache-control-ephemeral-param
output_config	anthropic-output-config
stream	boolean	(default: false)	default: false

Types

45 $defs

anthropic-base64-source-paramobject

type	enum		base64
media_type*	string	MIME type of the data, such as image/png or application/pdf.
data*	string	Base64-encoded bytes.

anthropic-cache-control-ephemeral-paramobject

type*	enum		ephemeral
ttl	enum		5m

anthropic-citations-config-paramobject

enabled

enum

false

anthropic-content-block-paramobject | object | object | …

anthropic-content-source-block-paramobject | object

anthropic-content-source-other-block-paramobject

type*

string

Any block type except text.

anthropic-content-source-paramobject

type	enum		content
content*	string \| anthropic-content-source-block-param[]	A string, or an array of content blocks. Non-text blocks are passed as their JSON text.

anthropic-content-source-text-block-paramobject

type*	enum		text
text*	string

anthropic-custom-tool-paramobject

type	enum		custom
name*	string
description	string		nullable
input_schema	object	JSON Schema for the tool's input.	nullable
parameters	any	Parameter schema, read only for the client tool search tool named ToolSearch.
strict	boolean		nullable
defer_loading	boolean		nullable
cache_control	anthropic-cache-control-ephemeral-param

anthropic-direct-caller-paramobject

type*

enum

direct

anthropic-document-block-paramobject

type	enum	document
source*	object \| object \| object \| …
title	string	nullable
context	string	nullable
citations	anthropic-citations-config-param
cache_control	anthropic-cache-control-ephemeral-param

anthropic-document-source-paramobject | object | object | …

anthropic-file-source-paramobject

type	enum		file
file_id*	string

anthropic-image-block-paramobject

type	enum	image
source*	object \| object \| object
cache_control	anthropic-cache-control-ephemeral-param

anthropic-input-messageobject

role*	enum		user \| assistant \| system \| developer
content*	string \| anthropic-content-block-param[]

anthropic-json-output-formatobject

type*	enum		json_schema
schema*	object

anthropic-media-source-paramobject | object | object

anthropic-metadata-paramobject

user_id

string

anthropic-output-configobject

effort	enum		low \| medium \| high \| xhigh \| max
format	anthropic-json-output-format

anthropic-plain-text-source-paramobject

type	enum		text
media_type	any	Ignored. Plain text is always text/plain.
data*	string

anthropic-redacted-thinking-block-paramobject

type	enum		redacted_thinking
data	any	The encrypted reasoning, as returned.
redacted_thinking	any	Older name for data, read when data is absent.

anthropic-search-result-block-paramobject

type	enum		search_result
source	any	Where the result came from.
title	any	Result title.
content	any	Text blocks with the result content.
cache_control	anthropic-cache-control-ephemeral-param

anthropic-server-tool-caller-paramanthropic-direct-caller-param

type*

enum

direct

anthropic-server-tool-use-block-paramobject

type	enum	server_tool_use
id*	string
name*	enum	web_search \| tool_search
input*	anthropic-server-tool-use-input-param
cache_control	anthropic-cache-control-ephemeral-param
caller	anthropic-server-tool-caller-param

anthropic-server-tool-use-input-paramobject

query

any

The search query.

anthropic-system-text-block-paramobject

type*	enum		text
text*	string
citations	any	Accepted and ignored.
cache_control	anthropic-cache-control-ephemeral-param

anthropic-text-block-paramobject

type	enum		text
text*	string
citations	any	Accepted and ignored.
cache_control	anthropic-cache-control-ephemeral-param

anthropic-thinking-block-paramobject

type	enum		thinking
thinking*	string
signature	any	Accepted and ignored.

anthropic-thinking-config-adaptive-paramobject

type	enum		adaptive
display	enum		summarized \| omitted

anthropic-thinking-config-disabled-paramobject

type

enum

disabled

anthropic-thinking-config-enabled-paramobject

type	enum		enabled
budget_tokens*	integer	Reasoning token budget. Must be less than max_tokens. (minimum: 1024)	n ≥ 1024 · format: int64
display	enum		summarized \| omitted

anthropic-thinking-config-paramobject | object | object

anthropic-toolobject | object | object

anthropic-tool-choiceobject

type*	enum		auto \| any \| none
name	any	Ignored.
disable_parallel_tool_use	boolean

anthropic-tool-result-block-paramobject

type	enum		tool_result
tool_use_id*	string
content	string \| anthropic-tool-result-content-block-param[]	A string, or an array of content blocks. Any other value is passed as its JSON text.
is_error	any	true marks the result as an error.
cache_control	anthropic-cache-control-ephemeral-param

anthropic-tool-result-content-block-paramobject | object | object | …

anthropic-tool-result-document-block-paramobject

type*	enum	document
source*	object \| object \| object \| …
title	string	nullable
context	string	nullable
citations	anthropic-citations-config-param

anthropic-tool-result-image-block-paramobject

type*	enum		image
source*	object \| object \| object

anthropic-tool-result-other-block-paramobject

type

string

Any block type except text, image and document.

anthropic-tool-search-tool-paramobject

type*	enum		tool_search \| tool_search_20250305
execution	enum		server \| client · nullable
description	string		nullable
parameters	object	Parameter schema for a client-executed tool search tool.	nullable
input_schema	any	Used as parameters when parameters is omitted.
cache_control	anthropic-cache-control-ephemeral-param

anthropic-tool-use-block-paramobject

type	enum		tool_use
id*	string
name*	string
input	any	Tool arguments, as an object.
cache_control	anthropic-cache-control-ephemeral-param

anthropic-url-source-paramobject

type	enum		url
url*	string

anthropic-user-location-paramobject

type	enum	approximate
city	string	nullable
region	string	nullable
country	string	nullable
timezone	string	nullable

anthropic-video-block-paramobject

type	enum		video
source*	object \| object \| object
fps	number	Frames per second to sample.	nullable
cache_control	anthropic-cache-control-ephemeral-param

anthropic-web-search-tool-paramobject

type*	enum	web_search \| web_search_20250305 \| web_search_20250305_15
user_location	anthropic-user-location-param
cache_control	anthropic-cache-control-ephemeral-param

Validate a payload

before you spend tokens

shell

$ curl -X POST https://modelschemas.com/v1/validate \
    -d '{"provider":"meta","endpointId":"v1/messages","payload":{…}}'
→ {"valid": false, "errors": [{"path": "#", "keyword": "required", …}]}