# Agent Harness Build Night

> A build night for making the harness behind AI agents, ending with demos and a community vote.

- When: Tue, November 17, 2026 18:00–21:30 JST
- Where: Shibuya, Japan · In person
- Region: Kanto (Tokyo)
- Organizer: +81Builders
- Language: JA/EN
- Source: Luma — https://lu.ma/5fjvo0ps
- Page: https://japantech.info/events/luma-5fjvo0ps/

## Summary

A hands-on night for building the agent "harness": the loop that drives the model, its tools, context and memory handling, execution permissions and evaluation. Participants may write a minimal agent loop from scratch, add tools or subagents to an SDK, or build an evaluation set.

After several hours of building, volunteers give 3-minute demos, and the project with the most votes is announced before the event closes.

Held in Shibuya with a capacity of 100. Participation is welcome in Japanese or English.

## About the community

+81Builders is a community for people building products in Japan, running hands-on gatherings open to both Japanese and English speakers. Sessions typically end with demos and a vote.

#ai-agents #agent-harness #build-night #hands-on #llm #hackathon #shibuya #evals #llm-tooling #neo4j