Series

LLM Interface Protocols

A factual map of the protocols, specs, and transport layers teams use to turn LLM responses into structured, trusted product interfaces — from output contracts and streaming to AG-UI, A2UI, and MCP Apps.

6 parts
  1. Part 1

    The protocol landscape for LLM interfaces

    A factual map of the open specs and transport layers that turn model output into product UI — from structured outputs and streaming to AG-UI, A2UI, and MCP Apps.

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  2. Part 2

    Output contracts: structured outputs and tool calling

    How JSON Schema, tool use, and typed objects form the first protocol layer between LLM responses and frontend interfaces.

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  3. Part 3

    Streaming protocols: from tokens to UI messages

    How text streams, SSE data streams, and UIMessage parts carry LLM output to the frontend — and what frontend engineers need from each.

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  4. Part 4

    AG-UI explained for frontend engineers

    What the Agent–User Interaction Protocol standardizes, how it differs from A2UI and MCP, and when your agentic frontend needs it.

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  5. Part 5

    A2UI explained for frontend engineers

    How Google's declarative agent UI spec lets LLMs propose native component trees across trust boundaries — without executing generated code.

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  6. Part 6

    MCP Apps explained for frontend engineers

    How the MCP Apps extension lets tools return interactive UI resources — and how it compares to A2UI and AG-UI for product teams building on LLM responses.

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