The Harness

Everything built around the model to make it useful: instructions, memory, access to documents and to tools.

The terms on this floor

22 entries

APINo. 040An API is a doorway meant for software: one program asks, another answers, in an agreed format. Like a vending machine: you explain nothing to a shop assistant, you put in what it expects and you receive what it returns.
assistantNo. 002An assistant is a product that waits for your message, answers you, then stops. Like a service desk: you ask a question, you are given an answer, and nothing happens as long as you ask for nothing. You lead the exchange, turn by turn.
chatbotNo. 015A chatbot is a program you exchange messages with, as at a counter: you ask a question, it answers, and everything happens in the thread. It is a way of presenting a service, not a particular technology.
chunkingNo. 065Chunking consists in cutting your documents into fragments before indexing them, since it is a fragment, and not a whole document, that the search will return. Like cutting a manual up into index cards: the cut decides what will be found again, and what will remain incomprehensible.
contextNo. 008The context is all the text the model has in front of it at the moment it answers: your question, the history, the documents you added. Like the file placed in front of someone before an interview: whatever is not in it does not exist for them.
few-shot promptingNo. 081Few-shot prompting means putting two or three examples of what you expect, input and output, into the request itself rather than describing it. Like handing someone three completed forms instead of explaining how to fill the form in.
guardrailsNo. 041Guardrails are the limits placed around an AI system so that its errors stay harmless: what it cannot trigger on its own, what a person has to approve. Like the railing on a balcony: it does not stop you leaning out, it stops the fall.
harnessNo. 003The harness is everything built around a model to make it useful: instructions, documents, tools, guardrails. Like a car around an engine: without a body, seats or steering wheel the mechanics still turn, but nobody goes anywhere.
MCPNo. 039MCP is a standard socket between the software that drives a model and the tools or documents it has to reach. Like a standardised electrical socket: every appliance plugs in without a bespoke cable, and changing one does not mean redoing the wiring.
memoryNo. 009Memory is what a product decides to keep between your exchanges, then to give the model to read when it is useful. Like a notebook kept by a colleague: they remember nothing, but they read their notes again before each meeting.
moderationNo. 044Moderation is the sorting of the content that enters and leaves an AI system: what you refuse to process, what you refuse to let through. Like the check at the door of a hall: you look at what crosses the threshold, in both directions.
promptNo. 010The prompt is the text you address to the model: your request, with what is needed to answer it. Like an instruction left for someone who arrives knowing neither you nor the file: the more precise it is, the less they improvise.
prompt cachingNo. 066Prompt caching keeps the work already done on the beginning of an input, so that a request starting with the same text does not have to do it again. Like a machine already brought up to temperature: the warm-up is not started again for every batch.
prompt engineeringNo. 067Prompt engineering is the work of formulating what you ask the model, with its examples and its output format, then checking that the wording holds on real cases. Like briefing a capable temporary worker who knows neither the organisation nor the file.
prompt injectionNo. 096Prompt injection means slipping into a text the system reads an instruction that takes precedence over the designer’s own, because the model receives both as a single stretch of text and cannot tell which one carries authority. Like an unsigned note slipped into a file handed to an employee: they read it along with the rest, and nothing on the paper says it did not come from management.
RAGNo. 013RAG means searching for the documents useful to your question, then giving them to the model to read before it answers: like a colleague who, before answering you, goes and pulls out the right binder and rereads it in front of you.
structured outputNo. 043A structured output is a response constrained to follow a precise shape, so that another piece of software can read it directly. Like a form rather than a free letter: the boxes are imposed, which says nothing about the accuracy of what you write in them.
system promptNo. 037The system prompt is the permanent instructions a product places ahead of every request: the tone, the role, the prohibitions. Like the rules posted at the entrance of a swimming pool: they hold for everyone, before you have said a word.
toolNo. 012A tool is an action the model can request from a piece of software: search the web, read a file, send a message. Like a diner in a restaurant: they order, they do not go into the kitchen, and the dish is brought to them.
tool callingNo. 038Tool calling is the moment when the model requests an action instead of writing: finding a file, sending a message. Like a customer filling in an order form: they write down what they want, someone else fetches it and brings it back to them.
vector databaseNo. 042A vector database stores texts by their meaning rather than by their words, so as to retrieve those that resemble your question. Like a shop aisle where neighbouring items serve the same purpose: you find what you need without knowing the exact name.
web searchNo. 064Web search is the tool that lets a model go and fetch pages online and read them before answering, instead of sticking to what it has learned. Like a librarian who goes out to consult the day’s newspapers rather than quoting from memory.

The other floors

The grid

The Elevator is the infographic that maps these four floors: one and the same request, read again at every level.