How can I restrict conversation context to just the last few messages in OpenAI Assistants?

Below is a summary of how you can achieve your goal:

Token and Message Control in a Run

While the documentation explains that the API automatically manages context by truncating messages to remain within the model’s maximum token limit, you do have some control:

• Token Limits:
  You can set parameters like max_prompt_tokens (and max_completion_tokens) when creating a Run. This tells the API how many tokens to consider for the prompt. If you set a lower limit, only the recent tokens (likely coming from the last few messages) will be used because older content is dropped to meet the limit.

• Recent Messages Option:
  The API also provides a way to specify the maximum number of recent messages to include. This feature means you can effectively restrict the conversation history to just the most recent 2 or 3 messages. However, note that it’s based on the number of messages rather than a direct token calculation.

How to Implement It

When configuring a Run, you might do something similar to the following:

JSONCopied
{
  "max_prompt_tokens": 500,
  "max_completion_tokens": 1000,
  "recent_messages_limit": 3,  // hypothetical parameter if available
  "other_run_configurations": "..."
}

Note:

• The most common control mechanism is through the token limits (like max_prompt_tokens), which will automatically truncate older messages.
• If you specifically need to limit the conversation to a fixed number of messages (e.g., exactly the last 2 or 3), you might need to manually manage the conversation context in your application. This means when initiating a new Run, you prepare a request that only includes these recent messages.

Summary

You cannot directly tell the Assistants API to "only use the previous 3 messages" in a single parameter; however, you can narrow the context by:

1. Setting a lower max_prompt_tokens value so that only recent tokens fall within the limit.
2. Utilizing any available options to restrict the number of recent messages if provided.
3. Optionally managing conversation history on your side to only send desired messages when starting a Run.

This approach helps reduce token usage and ensures optimal performance without sending the entire chat history.