Short answerThe context window is the maximum amount of text a model can consider at once. Instructions, retrieved file passages, the conversation and the answer all share it, so long instructions leave less room for everything else.
What fills it
- Your instructions (sent every time).
- Retrieved passages from your files.
- The conversation so far.
- The model's answer.
What it means
- Pasting whole documents into instructions may not fit; use retrieval instead (vector stores).
- Long chats eventually push older messages out.
- More text sent means higher cost: tokens.
Practical rules
Keep instructions concise, use retrieval for facts and limit how much history is sent. One platform's training-file option places files directly in the instruction so they must fit the model's context, which is why retrieval-based knowledge is better for big libraries. See TypingMind's options.
Check your GPT before you move it
Paste your instructions, file names and Actions schema into the free checker. It runs in your browser and builds a portable bundle. Nothing is uploaded.
Open the free checker