Elias Pardo

Quality Engineer
15+ years defining what to test, how, and why it matters

1 minute read

Part of my Quality Time Quality Growth series in LinkedIn.

The idea sounded so simple: “I want a chatbot that can quiz me and answer questions about the provided document.”

This sentence was the simple premise for building my RAG Chatbot quickly revealed that simplicity for humans doesn’t always translate to simplicity for LLMs.

The Two Modes

The application involved two distinct use cases, each with its own quirks:

  1. Exam Prep Chatbot: the user asks the LLM for a question, answers it and gets the correct response back !Sequence diagram

  2. Domain Expert Chatbot: the user asks a question about a particular topic, gets the answer back !Sequence diagram While all this seems trivial for a human, it’s not so straightforward for an LLM: I’ve seen all sorts of erratic behaviors including the chatbot turning the user’s answer into a new question, or returning entire conversations back-to-back as a single response.

The Problem

It looks like most of this drama was caused by the LLM trying to juggle too many conflicting instructions in a single prompt.

Taking a closer look, I only had issues with the first scenario (the exam prep mode), because it relies on memory. Without going into too much detail, there are mainly two things you can tweak:

  • A system prompt: telling the model to act like an instructor or expert in the subject matter
  • A condensed question prompt: which builds the actual query from the user input and chat history

The final prompt to the LLM is built as:

  • Final prompt: system prompt + context (provided by the retriever) + condensed question prompt Sequence diagram

Ultimately, asking the LLM to handle both exam-prep and domain-expert logic through a single prompt turned out to be too much cognitive load for both the model and for me. The challenge was that a single prompt created ambiguity for the LLM, leading to erratic behavior.

The “Solution”

So, me being pragmatic, I took the hit. Now I’m looking to simplify the app and add an operational mode selector: exam-prep or domain expert.

Next step is to implement that. Hopefully, no surprises. Stay tuned.

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