Skip to main content
POST
Create Message (Anthropic)
The Messages API provides Anthropic-style message creation for Claude models.

Create Message

POST /messages Create a message completion using Anthropic’s message format.

Request Body

model
string
required
The model to use for completion (e.g., “claude-3-sonnet-20240229”)
messages
array
required
An array of message objects
max_tokens
integer
required
Maximum number of tokens to generate
temperature
number
Temperature for randomness (0.0 to 1.0)
system
string
System message to set context

Response

Returns a message completion object with the generated response.

Example

Authorizations

Authorization
string
header
required

Enter your API key (starts with 'ek-')

Body

application/json
model
string
required
Example:

"claude-3-5-sonnet-20241022"

messages
object[]
required
max_tokens
integer

Maximum tokens to generate

temperature
number
Required range: 0 <= x <= 1
top_p
number
top_k
integer
stream
boolean
default:false
system
string

System prompt

tools
object[]
tool_choice
Available options:
auto,
any
thinking
object
reasoning_effort
enum<string>

Reasoning effort level. Silently ignored for models that do not support reasoning_effort.

Available options:
none,
minimal,
low,
medium,
high,
xhigh

Response

200 - application/json

Success

id
string
required
type
enum<string>
required
Available options:
message
role
enum<string>
required
Available options:
assistant
content
object[]
required
model
string
required
stop_reason
enum<string> | null
required
Available options:
end_turn,
max_tokens,
stop_sequence,
tool_use
usage
object
required
stop_sequence
string | null