Tools

When an agent runs a task, it can call tools to extend its capabilities. During a stream, every tool call produces a tool_start event followed by a tool_end event. You can parse these into typed objects to build UIs, logs, or audit trails.

Tool types

Agents on Compose have access to five tool families:

Tool	Tool name	What it does
Models	`models_call`	Calls a model for text, image, audio, or video generation
Connectors	`connectors_find`	Discovers external integrations like MCP servers and onchain tools
Agents	`agent_find`	Finds other deployed agents for delegation
Search	`search_call`	Runs a web search through a chosen provider
Catalog	`query_catalog`	Queries the catalog when the right tool family is unclear

A sixth tool name, swarm_delegate, belongs to the Agents family. It delegates a task to another agent after discovery. See Agents.

Parsing tool events

Use parseToolEvent() to turn a raw tool_start or tool_end event into a typed object. Each tool family has its own shape, so you can inspect the parsed result to know which tool ran.

import { parseToolEvent } from "@compose-market/sdk";

for await (const event of stream) {
  if (event.type === "tool_start" || event.type === "tool_end") {
    const tool = parseToolEvent(event);
    if (!tool) continue;

    if (tool.start) {
      console.log(`Tool started: ${event.toolName}`);
    } else if (tool.error) {
      console.error(`Tool failed: ${tool.error}`);
    } else {
      console.log(`Tool finished: ${event.toolName}`);
    }
  }
}

Common shape

Every tool event shares the same core fields:

Field	Type	Meaning
`start`	`boolean`	`true` on `tool_start`, `false` on `tool_end`
`action`	`string`	What the tool was asked to do
`result`	`object \| null`	The result payload (only on `tool_end`)
`error`	`string \| null`	Error message if the tool failed

Each family adds one more field that identifies the subject — model, connector, agent, mode, or domain. The pages below cover each one in detail.

Models

Model discovery and invocation.

Connectors

Connector discovery — MCP and onchain.

Agents

Agent discovery and delegation.

Search

Web search through the stream.

Catalog

Catalog queries for tool selection.

Getting Started

Payments

Agent Streaming

Slash Commands

Channels

Memory

Inference

Guides

Tools

Tool types

Parsing tool events

Common shape

Next

Models

Connectors

Agents

Search

Catalog

​Tool types

​Parsing tool events

​Common shape

​Next

Models

Connectors

Agents

Search

Catalog

Tool types

Parsing tool events

Common shape

Next