Build a Coding Agent with Tools, Skills and PydanticAI

We build a coding agent from scratch, starting with tool calls and an agentic loop. We add a skills system that loads reusable instruction files on demand, and the final version runs on PydanticAI.

The agent can read and write files, run shell commands, and search the codebase. It loads specialized skills too, all inside a structured Django project template.

We combine and update two earlier sessions here: Building a Coding Agent and Skills.md from Scratch.

What we cover:

• Tool calls with the OpenAI Responses API: from no tools to a full agent loop
• Building a coding agent with five core tools (read, write, tree, bash, search)
• Skills: reusable instruction files loaded by the agent on demand
• Porting the same agent to PydanticAI

This workshop was originally delivered at MLCon 2026 Amsterdam. There is no video recording available.

The agent you will build

The architecture of the final agent:

The agent runs inside a Django project template. It has five core tools for interacting with the filesystem and shell. A skills tool loads extra instructions from SKILL.md files when the agent finds them relevant.

We build it in four parts:

• Understand tool calls with the OpenAI Responses API.
• Build the coding agent with five core tools.
• Add the skills system.
• Port the same agent to PydanticAI.

Links

These workshops and resources are related:

• Previous coding-agent workshop - the v1 version without skills
• agent-skills workshop - the standalone skills workshop