Instructions

Instructions are what the model reads before it answers. A generated agent sets them on Agent({ ... }):

export const assistant = Agent({
  id: "assistant",
  name: "Order assistant",
  instructions:
    "Help with orders. Always use lookup_order for order questions.",
}).build();

instructions accepts one string or an ordered list. A string is normalized to a one-element array at build. Top-level instructions compile as capability id "agent". Named capabilities can add their own:

capability({
  id: "support",
  instructions: "Ask for an order number before using find_order.",
  tools: [findOrder],
})

Dynamic instructions

A before("turn") or before("step") hook can return a Patch with extra instructions. Turn-scoped patches apply to every model call in that turn; step-scoped patches apply to that model call only.

export const support = Agent({
  id: "support",
  instructions: "Help with orders.",
})
  .before("turn", ({ info }) => ({
    instructions: [`Tenant ${info?.tenantId ?? "unknown"}`],
  }))
  .build();

info is host identity from the Runtime session. It is not model-visible unless a hook copies it into instructions. See Hooks.

Do not put secrets in instructions, manifests, or hook patches that become history.

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