Agent Lore

What is a Modelfile?

A Modelfile is Ollama's recipe for a model. It sets the base model, system prompt, temperature, and other parameters. Create a custom model once, reuse it everywhere.

Create a coding assistant

Save this as

Modelfile

FROM llama3.2

SYSTEM """You are a terse Python expert.
Always include type hints.
Prefer standard library over dependencies."""

PARAMETER temperature 0.2
PARAMETER num_ctx 4096

Build and run

ollama create mycoder -f ./Modelfile
ollama run mycoder

Use cases

• Coding persona with strict style rules
• Review bot that only finds bugs
• Formatter that rewrites code to match conventions
• Spec writer that turns bullet points into tickets

Iterate quickly

Edit the Modelfile, rebuild, and test:

ollama create mycoder -f ./Modelfile
ollama run mycoder "Refactor this function to use list comprehensions"

Keep versioned Modelfiles in your repo to share personas with your team.