# pydantic-ai-harness

> Claude/Codex skill by [@pydantic](https://omgskills.com/library/pydantic/index.md) · 143 stars · Updated 2026-10-16

Extend Pydantic AI agents with capabilities from pydantic-ai-harness -- the Coder coding agent, file and shell tools in local or sandboxed workspaces (Modal, E2B, Sprites, smolvm), Code Mode, sub-agents and planning, memory and skills, context compaction, guardrails and spend limits, web research and browsers, hosted SaaS integrations, step persistence, and background agents on Render Workflows. Use when the user mentions pydantic-ai-harness or pydantic\_ai\_harness, imports a harness capability such as Coder, CodeMode, FileSystem, Shell, SubAgents, Memory, or ToolGuardrail, or wants a Pydantic AI agent that edits files, runs commands or agent-written Python, delegates, remembers, manages long context, stays within limits, or runs model and tool operations as chained Render task runs.

## Install

```sh
git clone https://github.com/pydantic/skills /tmp/skills && ln -s /tmp/skills/skills/pydantic-ai-harness ~/.claude/skills/pydantic-ai-harness
```

## From README

Building with Pydantic AI Harness Pydantic AI Harness is the official capability library for Pydantic AI. Core pydantic-ai ships the agent loop and the capabilities that need model or framework support (thinking, web search, MCP, tool search, workspaces, and provider-native compaction); the harness ships optional capabilities for longer, more involved work: a coding stack, sandboxes, delegation, memory, context management, and controls. Harness capabilities go in Agent(capabilities=\[...\]) and compose with each other and with core capabilities; a few supporting pieces, such as media stores and the ACP server entry point, are used directly instead. This skill covers pydantic-ai-harness. For the core framework -- agents, tools, structured output, hooks, workspaces, and testing -- use the building-pydantic-ai-agents skill.

## Links

- HTML page: https://omgskills.com/library/pydantic/skills/pydantic-ai-harness/
- GitHub: https://github.com/pydantic/skills
- Author: [@pydantic](https://omgskills.com/library/pydantic/index.md)

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