Enhanced Mode prompt length differs between REST API (20,000 chars) and Python SDK (4,096 chars)

[Funakoshi0524]

Summary

The Enhanced Mode prompt length limit documented for the REST API is 20,000 characters,
while the Python SDK documentation states a limit of 4,096 characters.
This discrepancy causes confusion for users expecting consistent behavior across SDK and REST API.

REST API Documentation

REST API documentation states that Enhanced Mode supports up to 20,000 characters for the prompt:

• REST API documentation

Python SDK Documentation

Python SDK documentation states that the prompt limit is 4,096 characters:

• Python SDK documentation

Expected Behavior

The Python SDK should either:

• support the same 20,000-character limit as the REST API,
  or
• clearly document why the SDK imposes a stricter limit.

Actual Behavior

• REST API allows 20,000 characters.
• Python SDK documentation states 4,096 characters.
• This inconsistency makes it unclear which limit is authoritative for SDK users.

Questions for SDK Team

1. Should the Python SDK support the REST API’s 20,000-character limit?
2. If not, what is the reason for the stricter SDK limit?
3. Should the SDK documentation be updated to clarify this discrepancy?

Environment

• Package: azure-ai-transcription

[github-actions]

Thank you for your feedback. Tagging and routing to the team member(s) best able to assist.

//cc: amber-yujueWang Ryan Hurey (@rhurey) xitzhang (@xitzhang) pankopon emilyjiji

[github-actions]

🎯 Agentic Issue Triage

Summary: The author reports a discrepancy between the REST API documentation (20,000-character prompt limit) and the Python SDK documentation (4,096-character limit) for the Enhanced Mode feature in azure-ai-transcription, and asks whether this reflects an actual SDK limitation or a documentation error.

📋 Issue Details

Package: azure-ai-transcription
Affected API: Enhanced Mode prompt length parameter
Scenarios:

• REST API docs state Enhanced Mode supports up to 20,000 characters for the prompt
• Python SDK docs state the limit is 4,096 characters
• Users are unsure which limit is authoritative when using the Python SDK

Root ask: Clarify whether the Python SDK enforces a 4,096-character limit (and why), or whether the SDK documentation should be updated to reflect the 20,000-character limit from the REST API.

🔎 Debugging / Reproduction Notes

This appears to be a documentation inconsistency rather than a code bug. No reproduction steps are provided since the issue can be verified by reading the two documentation pages.

Suggested investigation steps:

1. Check whether the Python SDK actually enforces a 4,096-character limit (e.g., via input validation in the SDK code) or whether this is purely a documentation error.
2. Verify the underlying REST API maximum prompt length and whether it is truly 20,000 characters.
3. If the SDK does not enforce a hard limit, update the Python SDK documentation to match the REST API's 20,000-character value.
4. If the SDK does enforce a stricter limit, add documentation explaining the rationale for the difference.

🏷️ Label Confidence

• Category: Client — azure-ai-transcription is a data-plane client library located under /sdk/transcription/
• Service: Speech Transcription — the package azure-ai-transcription maps directly to the Speech Transcription service entry in CODEOWNERS
• Confidence: High — package name and SDK path unambiguously identify the service and category

👥 Owner Routing

• Matched CODEOWNERS entry: # ServiceLabel: %Speech Transcription (~line 762) — matched on the predicted service label
• AzureSdkOwners: none listed
• ServiceOwners: @amber-yujueWang @rhurey @xitzhang @pankopon @emilyjiji
• Routing action: Added Service Attention and needs-team-attention labels; ServiceOwners tagged via routing comment
• Scan notes: Scanned from bottom of CODEOWNERS upward; %Speech Transcription entry was found with only # ServiceOwners (no # AzureSdkOwners), so the Service Attention path was used

Generated by Agentic Triage for issue #48423 · 28.8 AIC · ⌖ 5.84 AIC · ⊞ 9.6K · ◷