Catalog

Sometimes an agent receives a request and isn’t sure which tool family to use — should it call a model, find a connector, or delegate to another agent? When the right family is unclear, the agent queries the catalog first. The tool name for this is query_catalog.

How it works

The catalog is a registry of everything available to the agent: models, connectors, and other agents. By querying it, the agent can decide which family fits the task before committing to a specific tool call. The domain field on the event tells you which family the catalog returned.

Domain	Meaning
`models`	The catalog pointed the agent toward model invocation
`connectors`	The catalog pointed the agent toward connector discovery
`agents`	The catalog pointed the agent toward agent delegation

After the catalog query resolves, you will typically see a follow-up tool call from the matching family — for example, a models_call after a catalog query with domain: "models".

Event shape

A parsed catalog tool event has these fields:

Field	Type	Meaning
`start`	`boolean`	`true` when the query begins, `false` when it ends
`domain`	`string`	The tool family the catalog selected
`action`	`string`	What the agent was trying to accomplish
`result`	`object \| null`	The catalog response, available on `tool_end`
`error`	`string \| null`	Error message if the query failed

Stream example

for await (const event of stream) {
  if (event.type === "tool_start" && event.toolName === "query_catalog") {
    const tool = parseToolEvent(event);
    console.log(`Querying catalog for: ${tool?.action}`);
  }
  if (event.type === "tool_end" && event.toolName === "query_catalog") {
    const tool = parseToolEvent(event);
    if (tool?.error) {
      console.error(`Catalog query failed: ${tool.error}`);
    } else {
      console.log(`Catalog recommends: ${tool?.domain}`);
    }
  }
}

Display metadata

The display object includes a summary of what the catalog found. Use display.summary to show the catalog’s recommendation in your UI before the follow-up tool call arrives.

Getting Started

Payments

Agent Streaming

Tools

Slash Commands

Channels

Memory

Inference

Guides

How it works

Event shape

Stream example

Display metadata

​How it works

​Event shape

​Stream example

​Display metadata

How it works

Event shape

Stream example

Display metadata