Which Hook for Which Job

CopilotKit Vue has composables for registering agent behavior and for deciding how agent output appears in chat. Call them from a component rendered below CopilotKitProvider, where Vue can inject the CopilotKit context.

The 30-second version#

Composable	Use it when you want to
useFrontendTool	Give the agent a browser-side tool, optionally with inline UI.
useRenderTool	Render a named tool call, or use name: "*" as the fallback.
useDefaultRenderTool	Install the built-in or a custom fallback for otherwise-unrendered tool calls.
useComponent	Register a Vue component as a named frontend tool renderer.
useHumanInTheLoop	Pause a frontend tool until a user supplies a response.
useInterrupt	Handle an agent interrupt and resume or cancel it.
useRenderActivityMessage	Resolve a registered activity-message renderer for a custom surface.
useRenderCustomMessages	Resolve registered before/after message renderers for a custom surface.

How to choose#

• The agent should run something in my app. Use useFrontendTool. Define its schema and handler; add render when the call also needs inline UI.
• A tool call should look different. Use useRenderTool for one named call, useComponent for a component-first frontend tool, or useDefaultRenderTool for the fallback. In the prebuilt chat, named tool-call-<toolName> and tool-call slots are the idiomatic template customization path.
• The agent must stop for user input. Use useHumanInTheLoop for a tool-level approval or input gate; use useInterrupt for an agent-initiated interrupt that you resolve or cancel.
• I am building my own surface. Use useAgent for reactive messages and run state, useCopilotKit for the runtime handle, and the activity/custom message composables when you need those registered renderers.

Tool versus renderer#

useFrontendTool and useComponent register tools that an agent can call. useRenderTool and useDefaultRenderTool only control presentation, so they can render a backend tool without adding a browser handler. Vue components and templates should use slots for chat composition; composables remain useful for programmatic registration and custom surfaces.

Related#

• Frontend Tools
• Generative UI: tool-based UI and tool rendering
• Human in the Loop
• Slots