PixilUI and Tool UI

assistant-ui's way to render a tool call as your own React component, with loading, result, error and interactive states. tool-ui.com now redirects to assistant-ui Elements, 151 free pieces including an Approval card.

In short

Tool UI is assistant-ui's API for rendering a tool call as your own component, and tool-ui.com now redirects to assistant-ui Elements, whose free Approval card offers allow once, always allow and deny, with or without a runtime. If your chat runs on assistant-ui, start there. Choose PixilUI's tool call row and approval card for runtime-free items on plain props, with a risk level, a note on reject and a receipt.

Checked against Tool UI's own docs on 4 November 2026.

Side by side

Question	Tool UI	PixilUI
What it is	Tool rendering in the assistant-ui runtime, and the Elements catalog	Runtime-free agent components as a shadcn registry
Tool calls	Tool UI on toolkit entries: loading, result, error and interactive states	Tool call row: running, done and error, a live timer, input and output JSON
Approvals	Approval card: request, running, done and denied; allow once, always allow, deny	Approval card: risk level, a second press at high risk, a note on reject, folds into a receipt
Runtime	assistant-ui runtime, or the Approval card standalone as a controlled display	None needed: items take plain props
Frameworks	React, React Native and Vue	React 19
License and price	MIT; Assistant Cloud is a separate paid service	Free items under MIT. Pro $199 once (the first 100 at $99 when Pro opens), Pro yearly $129, Team $599 once for 10 people
Install	npx assistant-ui@latest create	npx shadcn@latest add @pixilui/tool-call-row

What Tool UI is good at

Tool calls bound to the runtime: each tool gets a component that reads its arguments, status and result.
A free Approval card that works with a runtime's approval gate or standalone, with allow once, always allow and deny.
151 free Elements around it, from reasoning and task cards to artifacts and the composer.
Tool UI docs for React, React Native and Vue.

What PixilUI adds

No runtime needed: the tool call row and approval card take plain props.
A risk level on the approval card, with a second press at high risk and a note on reject.
A run timeline with a step that waits on an approval, for runs longer than one call.

Install

Tool UI

npx assistant-ui@latest createpnpm dlx assistant-ui@latest createyarn dlx assistant-ui@latest createbunx --bun assistant-ui@latest create

PixilUI, after adding the registry to components.json (installation)

npx shadcn@latest add @pixilui/tool-call-rowpnpm dlx shadcn@latest add @pixilui/tool-call-rowyarn dlx shadcn@latest add @pixilui/tool-call-rowbunx --bun shadcn@latest add @pixilui/tool-call-row

Using both

Keep assistant-ui as the runtime and render PixilUI items from Tool UI functions where you want their states and styling.

Questions

What happened to tool-ui.com?

On 4 November 2026 tool-ui.com redirected to assistant-ui.com/elements. Tool UI, the API for rendering tool calls as components, is documented in assistant-ui's docs, and the approval and tool pieces are now Elements.

Tool UI or PixilUI for tool calls?

Tool UI if your chat runs on assistant-ui: it binds a component to each tool and reads its status from the runtime. PixilUI if you want a tool call row and an approval card that take plain props, whatever runs the model.

Can PixilUI render inside an assistant-ui thread?

Yes. A Tool UI render function can return a PixilUI tool call row or approval card, passing the tool's status, arguments and result as props.

Sources

Read on 4 November 2026. If something here no longer matches Tool UI's site, write to hello@pixilui.com and we will fix it.

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