GlossaryFloor 3 · The Agentthe block caught in a loop: it starts again until it gets thereFloor 3 · The Agent
agent
No. 001 · v2026-08FR: agentAn agent is a system that puts a model to work in a loop to reach a goal: it plans, acts, sees the result and starts again, like a person following a recipe, tasting and adjusting at each step.
What it is not
An agent is not a cleverer assistant. An assistant waits for your message, answers, then stops: you remain the engine of the exchange. An agent receives a goal and chains the steps without handing control back to you at each one. Nor is it a model: the model is the engine, the agent is the system that runs it in a loop.
In depth
The loop
The heart of an agent is the agentic loop: the model receives the goal and the state of the work, chooses an action, carries it out through tools (reading a file, calling an API, running a search), observes the result, then decides what comes next. The output of one turn becomes the input of the next, until the goal is reached or the system stops.
What surrounds it
An agent never lives alone: it runs inside a harness that supplies its tools, its working memory and its guardrails. The decisive distinction is with the workflow: in a workflow, the sequence of steps is written in advance by a human; in an agent, the model chooses the next step. A workflow is predictable and replayable, an agent is adaptive and expensive to guarantee.
The trap
The main trap is compounding reliability: a system that is 95% reliable per step is only 60% reliable after ten steps. This is why serious agents come with evals, with traces and with a human in the loop at irreversible points. Autonomy is not a switch, it is a slider set risk by risk.
Relations where the neighbours live
- Requires
- Floor 1 · The Modela solid block on its own: the prediction machinelarge language modelFloor 2 · The Harnessthe block and its bolted-on plates: what gets added to ittool
- Often confused with
- Floor 2 · The Harnessthe block and its bolted-on plates: what gets added to itassistantFloor 2 · The Harnessthe block and its bolted-on plates: what gets added to itchatbot
Check 3 questions · click your answer
Level 1 · Recognise
Your company rolls out an HR chat that answers employees’ questions, one answer per message. Is it an agent?
Level 2 · Distinguish
What fundamentally distinguishes an agent from an automated workflow?
Level 2 · Distinguish
Why does the reliability of an agent degrade faster than that of a single answer?
Who works with this 2 roles
The roles for which this term is part of the ordinary work.
Lexigraph, "Agent", v2026-08, https://www.lexigraph.org/en/agent/, CC BY 4.0.