Call a Golem tool from Rust

Call an existing tool through a generated client

Load golem-generating-tool-clients for built-in releases and MCP imports. Add the tool to the Rust component’s dependencies.tools and configure its runtime binding separately. golem build automatically generates the client without an explicit bridge selection. Add a local Cargo dependency on the generated crate, relative to the consumer manifest:

[dependencies]
bash-tool-guest-client = { path = "../golem-temp/bridge-sdk/rust/internal/bash-tool-guest-client" }

Inside an async agent method, call the built-in bash release 0.2.1:

use bash_tool_guest_client::BashClient;
 
match BashClient::new().run("printf 'hello\\n'".into(), "".into(), 600).await {
    Ok(result) => println!("{}", result.stdout),
    Err(error) => eprintln!("tool invocation failed: {error}"),
}

The script’s exit_code is part of the result; check it when a nonzero exit should fail the agent method. A command with output attachments instead returns a ToolInvocation; use its collection helper to drain both channels concurrently and check the result and output outcomes separately. Use the generated signature for MCP structured results rather than assuming the call returns a string.

Call from a definition owned by the application

#[tool_definition] generates a <Tool>Client. Its async methods return Result<T, ToolError<E>>, where E is the tool’s declared error type:

use golem_rust::agentic::ToolError;
 
let client = EchoClient::default();
match client.echo("hello".to_string()).await {
    Ok(value) => println!("{value}"),
    Err(ToolError::Tool(error)) => eprintln!("declared tool error: {error:?}"),
    Err(error) => eprintln!("tool invocation failed: {error}"),
}

The default client targets the definition’s tool name. Use the generated named-target constructor only when deployment assigns another tool registration name. Do not treat protocol errors as the tool’s declared domain error. Drop or finish any stream handles according to the generated method signature.