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ManualAPI GuideAPI Reference
  • Overview
    • API Reference
    • Client libraries
  • API Reference
      • POSTMessages
      • POSTCount tokens in a Message
      • POSTValidate Messages Request
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API ReferenceMessages

Count tokens in a Message

POST
https://host.com/v1/messages/count_tokens
POST
/v1/messages/count_tokens
$curl -X POST https://host.com/v1/messages/count_tokens \
>     -H "Content-Type: application/json" \
>     -d '{
>  "model": "default",
>  "messages": [
>    {
>      "role": "user",
>      "content": "Count tokens for this input."
>    }
>  ],
>  "system": [
>    {
>      "text": "You are a tokenizer."
>    }
>  ],
>  "tools": [
>    {
>      "name": "get_weather",
>      "description": "Get current weather for a city.",
>      "inputSchema": {
>        "properties": {
>          "city": {
>            "description": "City name.",
>            "type": "string"
>          }
>        },
>        "required": [
>          "city"
>        ],
>        "type": "object"
>      }
>    }
>  ],
>  "thinking": {
>    "enabled": false
>  },
>  "tool_choice": {
>    "type": "auto",
>    "disable_parallel_tool_use": false,
>    "validation_mode": "lazy"
>  }
>}'
1{
2  "input_tokens": 1
3}
Count tokens in a Message
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Validate Messages Request

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Request

This endpoint expects an object.
modelstringRequiredDefaults to default
Model identifier or alias.
messageslist of objectsRequired
Conversation messages for the request.
systemlist of objectsOptional

System prompt input. Accepts str, list[str], System, list[System], or null. It is normalized internally to list[System].

toolslist of objectsOptional
Optional tool definitions.
thinkingobjectOptional
Thinking configuration.
tool_choiceobjectOptional
Tool selection policy.
output_configobjectOptional
Optional output configuration options.
cache_controlobjectOptional

Optional request-level cache control.

Response

This endpoint returns an object.
input_tokensinteger
Estimated number of input tokens for the provided payload.

Errors

401
Unauthorized
422
Unprocessable Entity