concepts

Agents

An AI agent takes a goal, picks its own tools, does the work, and checks the result. What that means in practice, and where agents are used today.

Context engineering

Context engineering is deciding what a model sees on each call. Why long chats get worse, and the habits that keep an agent sharp.

Effort level

Effort level is a dial for how hard a model thinks before it answers. Turn it up for hard problems, turn it down for speed and lower cost.

Evals

An eval is a test for AI output: run a prompt or skill over real examples and score the results. Which checks to automate, and which need a judge.

Fine-tuning

Fine-tuning trains an existing model further on your own examples, so the behavior you want is baked in instead of prompted every time.

Harness

A harness is everything wrapped around a model that turns it into a working [agent](/ai-field-guide/agents). Tools, memory, workspace, the loop that keeps it running.

Local vs cloud AI

AI in the browser runs in the cloud, outside your computer's trust boundary. Desktop AI tools are installed locally, so they can reach your files.

MCP

MCP is a standard way to plug an AI into your tools and data, replacing a custom connector per service with one shared protocol.

Open, open-weight, and proprietary models

Proprietary models stay on the company's servers. Open-weight models you download and run yourself. What each label actually means.

Personal Agent Protocol (Poppy)

Personal Agent Protocol (Poppy) is a draft standard for how your AI agent signs in and acts with a company for you, and how it relates to MCP.

Prompt injection

Prompt injection hides instructions inside text an AI reads, and the model follows them as if they came from you. Why it works, and how to limit it.

RAG

RAG searches your documents for the relevant parts, then hands those to the model with the question, so the answer comes from your data.

Skills

A skill is a folder that teaches an agent to do one task your way, every time. What goes in a SKILL.md, and how to keep a library of skills useful.

Tokens

A token is the chunk of text a model reads and writes in, roughly four characters. Why pricing and context limits are both counted in them.

Vibe coding

Vibe coding means describing what you want in plain language and letting AI write the code without reading it. Where it works, and where it breaks.