Prompt
The text supplied to a language model to elicit a response.
A prompt is the input given to a Large Language Model. In modern systems it is not a single string but an assembled structure: a System Prompt establishing role and rules, a sequence of conversational turns, the definitions of any available tools, and whatever documents or state have been injected for the task.
Two properties are worth internalising. First, everything in that assembly is text the model reads — including tool descriptions, which are frequently more influential on behaviour than the instructions written for the purpose. Second, everything competes for the same Context Window, so adding instruction has a cost, not just a benefit.
Prompts are also the least type-checked part of most systems. Nothing errors when a prompt describes a capability that was removed, states a rule the runtime does not enforce, or duplicates a fact that has since changed elsewhere. That makes them a prime site for Documentation Rot, and it is the argument for keeping a single source of truth: a tool's description ships beside its implementation and cannot drift, while a catalogue of tools in a separate document will.
See also5
Hand-picked in the note itself — the neighbours worth reading next.
Prompt Engineering
Shaping a model's input to make the desired behaviour reliable rather than occasional.
Agents & Language Models18 connections
System Prompt
The standing instructions that frame every turn of a conversation with a model.
Agents & Language Models14 connections
Tool Use
Giving a model a set of callable functions so it can act on the world rather than only describe it.
Agents & Language Models24 connections
Token
The sub-word unit a language model actually reads and writes; the unit of cost and of context.
Agents & Language Models13 connections
Prompt Injection
Untrusted content that reaches a model's context and is treated as instruction.
Agents & Language Models12 connections
Related2
Nearby in the graph rather than deliberately chosen. Looser, sometimes surprising.
Linked from9
Notes elsewhere in the wiki that reach for this one.
- Agent MemoryAgents & Language Models
Durable facts stored outside the context window and recalled into later sessions.
- Agent SkillAgents & Language Models
A packaged, invocable set of instructions that loads into an agent's context on demand.
- Context WindowAgents & Language Models
The bounded span of tokens a model can attend to in a single request.
- Large Language ModelAgents & Language Models
A neural network trained to predict text, used as a general-purpose instruction-following system.
- Model Context ProtocolAgents & Language Models
An open protocol for exposing tools, data, and prompts to AI applications through a uniform interface.
- Prompt EngineeringAgents & Language Models
Shaping a model's input to make the desired behaviour reliable rather than occasional.
- Prompt InjectionAgents & Language Models
Untrusted content that reaches a model's context and is treated as instruction.
- System PromptAgents & Language Models
The standing instructions that frame every turn of a conversation with a model.
- TokenAgents & Language Models
The sub-word unit a language model actually reads and writes; the unit of cost and of context.