Context window
A model's context window is the maximum number of tokens -- the prompt, any system instructions, tool definitions, retrieved content and the model's own output -- it can process in a single request, a limit set per model by its own vendor rather than by any shared industry specification. Everything an AI agent feeds into a request has to fit inside this budget together, which means a tool response, a retrieved document or an MCP resource competes for the same space as the user's own instructions. This matters for security as well as capacity: text embedded in a long tool response or fetched document sits in the same context window as trusted instructions, with nothing in the window itself distinguishing the two, which is exactly the gap prompt-injection defenses have to close outside the model.
By AdminKit team, Netbase JSC · Updated