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The genai_is_truncated function checks whether an AI model response was truncated due to reaching token limits or other constraints. It analyzes the finish reason returned by the API to determine if the response was cut short. You can use this function to identify incomplete responses, monitor quality issues, detect token limit problems, or track when conversations need continuation.

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For users of other query languages

If you come from other query languages, this section explains how to adjust your existing queries to achieve the same results in APL.
In Splunk SPL, you would check the finish_reason field manually.
| eval is_truncated=if(finish_reason="length", "true", "false")
In ANSI SQL, you would check the finish_reason field value.
SELECT 
  conversation_id,
  CASE WHEN finish_reason = 'length' THEN true ELSE false END as is_truncated
FROM ai_logs

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Usage

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Syntax

genai_is_truncated(messages, finish_reason)

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Parameters

NameTypeRequiredDescription
messagesdynamicYesAn array of message objects from a GenAI conversation. Each message typically contains role and content fields.
finish_reasonstringYesThe finish reason returned by the AI API (such as ‘stop’, ‘length’, ‘content_filter’, ‘tool_calls’).

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Returns

Returns a boolean value: true if the response was truncated (typically when finish_reason is ‘length’), false otherwise.

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Example

Check if a GenAI response was truncated due to token limits. Query 
['genai-traces']
| extend finish_reason = ['attributes.gen_ai.response.finish_reasons']
| extend is_truncated = genai_is_truncated(['attributes.gen_ai.input.messages'], finish_reason)
| summarize 
    truncated_count = countif(is_truncated),
    total_count = count(),
    truncation_rate = round(100.0 * countif(is_truncated) / count(), 2)
Output
truncated_counttotal_counttruncation_rate
4514503.10
This query tracks the rate of truncated responses, helping you identify when token limits are causing quality issues.
  • genai_estimate_tokens: Estimates token count. Use this to predict if responses might be truncated before making API calls.
  • genai_conversation_turns: Counts conversation turns. Analyze this alongside truncation to understand context length issues.
  • genai_extract_assistant_response: Extracts assistant responses. Use this to examine truncated responses.
  • strlen: Returns string length. Use this to analyze the length of truncated responses.