GitHub Copilot

Covers agent mode in VS Code, the Copilot CLI and the cloud coding agent.

npx shibbo init copilot

What it writes

The rules go into AGENTS.md. Copilot also reads .github/copilot-instructions.md and .github/instructions/*.instructions.md with an applyTo glob.

The MCP server for VS Code goes into .vscode/mcp.json. Note the servers key and type:

{ "servers": { "shibbo": { "type": "stdio", "command": "npx", "args": ["shibbo", "mcp"] } } }

The CLI doesn't read that file, so its server entry goes into .mcp.json with the usual mcpServers key.

An experimental hook goes into .github/hooks/shibbo.json, the one location the cloud agent reads:

{ "version": 1, "hooks": { "postToolUse": [{ "type": "command", "bash": "npx shibbo hook post-edit --for copilot", "timeoutSec": 30 }] } }

The cloud coding agent

Set its MCP server in the repo's settings, under Copilot, then MCP servers. It requires a tools list:

{ "mcpServers": { "shibbo": { "type": "local", "command": "npx", "args": ["shibbo", "mcp"], "tools": ["*"] } } }

How feedback reaches the agent

postToolUse returns {"additionalContext": ...}, which Copilot appends to the tool result. Exit code 2 is only a warning in Copilot, so shibbo always answers through stdout JSON. The name and argument shape of the edit tool aren't documented; shibbo reads the path from toolArgs, which is why the hook is marked experimental.

Sources: custom instructions, VS Code MCP, CLI MCP, hooks reference.