A deep dive into the GitHub Copilot SDK's ToolSet API, showing how to control which built-in tools (file read/write, shell execution, web fetch, etc.) are available to an agent session. Covers the AvailableTools and ToolSet properties on SessionConfig, the AddCustom and AddBuiltIn methods for explicit opt-in control, the built-in tool catalog with their IDs, the OverridesBuiltInTool flag for custom tool precedence, and how combining ToolSet filtering with PermissionHandler.ApproveAll creates a clean security boundary. Also explains why limiting available tools improves model behavior by reducing unnecessary tool calls and latency.
Table of contents
Enter AvailableTools and ToolSetThe built-in tool catalogWhy this matters beyond securityThe OverridesBuiltInTool flagCombining it all: a practical patternWhat about when you want all built-ins?More information380 Impressions