---
title: Agent tools
description: Describe selected views and actions for agent clients.
---

A view, lookup, or action becomes an agent tool only when you call
`.setAgentOptions({ description })` on its definition. The `agentOptions`
property returns that configuration. `toAgentTool()` returns a tool description,
or `undefined` when the definition has no agent options.

<BacklitExample path="agents/basic" view="tools" />

`resource.toAgentTools()` collects opted-in views, lookups, and actions. `resource.views()`
`resource.lookups()`, and `resource.actions()` return definitions in registration order.
An app host can use `app.resourceNames()` and `app.loadResource(name)` to collect
tools across resources.

A tool name is `resource_name`. A view tool has `mutates: false` and describes
a link. An action tool has `mutates: true` and describes an action. These are
data objects. The SDK does not start an agent server or execute model calls.
The host must route calls through `app.renderView` or `app.handleAction`.

A view tool input contains its address parameters as strings. An action input
combines address parameters and schema properties into one object. No address
parameter can have the same name as a payload property.
The action schema must expose a Standard JSON Schema input converter.
A missing converter throws `E_AGENT_SCHEMA_WITHOUT_JSON`. A name collision
throws `E_AGENT_PARAM_COLLISION`.

Apply authorization in middleware and handlers. Tool descriptions do not grant
access. See [Request handling](/reference/requests).

## Lookup tools

A lookup also supports `setAgentOptions`, `agentOptions`, and `toAgentTool`.
Its input has a required string `query` plus its address parameters. It has
`mutates: false`. Route it through `app.handleLookup` to return records.
Set `search: true` in its agent options to identify the resource search lookup
for a host that uses that flag. The tool descriptor itself contains the lookup
address, description, input, and mutation flag.