gRPC Sidecars: Writing Skills in Any Language
One of GoClaw's most powerful features is its gRPC sidecar system — a simple, language-agnostic way to extend the agent with new capabilities. In this post we'll walk through exactly how it works under the hood and build a complete Notion page-creation skill from scratch in Python.
How the proto contract works
Every skill sidecar implements a single gRPC service defined in pkg/proto/skill.proto. The interface is intentionally minimal:
When GoClaw starts, it connects to all configured sidecar addresses and calls Register to fetch the skill's OpenAI-compatible tool definition. These definitions get injected into every LLM prompt automatically — no extra wiring needed.
Building a Notion skill in Python
Here's a minimal but production-ready Notion page-creation skill:
Connecting to GoClaw
GoClaw will connect on startup, call Register to get the tool definition, and from that point on the LLM can call create_notion_page just like any built-in skill.