The anatomy of an agent

THE NEW PROBLEM

WHAT IT'S MADE OF

The shared core stays lit. Each form adds its own layer.

LLM callsthe reasoning engine every form shares

Context windowthe working memory it thinks in

Toolshands: how thinking becomes action

MCP serverssystems of record, KBs, data: one connector

Instructionsthe job, the rules, the disposition

Memorywhat survives past the session

The authored grapha person decides the steps, in advance

Per-node promptseach box tuned to one narrow job

Hard-wired toolsbound at build time, per step

Step-level teststhe steps are the product, so test the steps

The looplook, think, act, repeat; the LLM decides

Long-running taskscheckpoints & deferred answers: hours, not turns

Compaction & rolling windowssqueeze the history, keep going

Memory fileswhat matters, written down outside the window

Subagentsfresh windows for subtasks; attention budgeting

Skillsprocedural know-how, loaded on demand

Pluginsthe container: skills, tools, rules, shipped together

Tool discoveryfind capabilities at run time, not build time

Carried guardrailsthe package brings its own limits

Outcome evalsjudge the result, not the steps

THE PARTS