Calling Another Agent (Rust)

Overview

The #[agent_definition] macro auto-generates a <AgentName>Client type for each agent, enabling agent-to-agent communication via RPC. An awaited call blocks the calling agent until the target agent returns a result.

Getting a Client

Use <AgentName>Client::get(...) with the target agent’s constructor parameters:

let counter = CounterAgentClient::get("my-counter".to_string());

This does not create the agent — the agent is created implicitly on its first invocation. If it already exists, you get a handle to the existing instance.

Awaited Call

Call a method and wait for the result:

let result = counter.increment().await;
let count = counter.get_count().await;

The calling agent blocks until the target agent processes the request and returns. This is the standard RPC pattern.

Phantom Agents

To create multiple distinct instances with the same constructor parameters, use phantom agents. See the golem-multi-instance-agent-rust guide.

Cross-Component RPC

When calling agents defined in a different component, the generated client type is available after running golem build — the build step generates bridge SDK code for inter-component dependencies declared in golem.yaml.

Avoiding Deadlocks

Never create RPC cycles where A awaits B and B awaits A — this deadlocks both agents. Use trigger_ (fire-and-forget) to break cycles. See the golem-fire-and-forget-rust guide.