Assistant SDK overview

Documentation Index

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The Assistant SDK is the embed path for Metabind. It packages an MCP-aware AI client, conversation state, and the BindJS native renderer into a single SDK you drop into your app. Configure how it should reach an LLM, give it a host surface, and the SDK handles the rest.

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What the SDK gives you

The result: your users get a chat-like assistant that can call your Metabind tools and render the results in true native components — no web view, no rebuild for layout changes, no release cycle when you add a tool.

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Use the Assistant SDK when

• You’re building an iOS, Android, or web product and want an in-product AI assistant.
• You want to ship MCP tools that you built (in Metabind) without exposing a third-party MCP host to your users.
• You want native UI rendering of tool results — SwiftUI, Compose, React — not WebViews.
• You want Metabind to manage LLM key custody and the tool loop server-side (the default).

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Use a connected MCP host instead when

• Your users already work in Claude Desktop or ChatGPT, and you want to extend those surfaces.
• You don’t want to ship a UI yourself — connecting to an existing host is faster.
• The use case is developer-facing rather than end-user-facing.

A project’s tools work in both modes simultaneously. You can ship an Assistant SDK in your app and let power users also connect Claude Desktop to the same project.

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Three platforms, one model

Each SDK exposes the same shape — a MetabindAssistant configured with a server and an LLMProvider, plus a default MetabindAssistantView chat surface — adapted to the platform’s idioms. The web release is React-only today; non-React frameworks can use @bindjs/renderer directly.

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Two ways to reach an LLM

The SDK is provider-pluggable through an LLMProvider abstraction. Two implementations ship:

• MetabindAgentProvider — calls Metabind’s hosted Agent proxy at agent.metabind.ai. The proxy authenticates with a Metabind project token, holds the LLM key, runs the tool loop server-side, and streams responses back as SSE. The proxy supports Anthropic, OpenAI, and Google — selected per-project in MCP App Studio. Recommended for production.
• AnthropicProvider — bring-your-own-key (BYOK) Anthropic, called directly from the client. Useful for development, internal tools, or apps where the key reaches the SDK from an authenticated user-managed source.

Custom providers can implement the public LLMProvider protocol if you need to integrate something else. See LLM provider configuration.

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What you bring

• A Metabind project with at least one published Type. The SDK connects to its production endpoint by default; you can override to draft for testing.
• A Metabind project token (for Agent proxy mode), or an Anthropic API key (for BYOK mode). Mint project tokens server-side so they aren’t hard-coded in the binary.
• A surface in your app to render the assistant — a screen, a sheet, a sidebar, an inline panel. The SDK ships default UI, but you can fully replace it.

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What you don’t write

• Tool calling logic. In Agent proxy mode the proxy runs the loop; in BYOK mode the SDK does. Either way you don’t.
• Streaming. SSE deltas flow into the conversation state and re-render the UI.
• Native rendering. Interactive Tool output renders through BindJS without you wiring it up.
• Schema validation. Inputs and outputs are validated against the project’s tool schemas before they reach the renderer.

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Token and key handling

For production, prefer the Agent proxy — your binary ships only a Metabind project token, and there is no third-party LLM key to leak.

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Conversation state

The SDK maintains conversation state in memory by default — useful for ephemeral chats. For persistence across launches or reloads, read assistant.conversation.messages, serialize to your platform’s storage, and rehydrate on next launch. For multi-device conversations (start on iPhone, continue on iPad), persist the conversation server-side and resume by ID.

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Native rendering details

When a Metabind Interactive Tool returns, its UI resource is handed to the SDK’s renderer:

• iOS: Rendered as SwiftUI views. Embedded inside your View hierarchy.
• Android: Rendered as Composables. Embedded inside your @Composable tree.
• Web: Rendered as React components. Embedded inside your React tree.

The renderer respects your app’s typography, color scheme, and accessibility settings — it’s a native view rendered by your platform’s UI runtime, not an iframe or WebView.

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What ships in the SDK

• Default chat surface (MetabindAssistantView) with sender + assistant messages.
• Native rendering of Interactive Tool output via BindJS.
• MetabindAgentProvider (proxy) and AnthropicProvider (BYOK direct) on iOS, Android, and web.
• Custom LLMProvider implementations for anything else.

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