Nano Agent
Nano Agent is a Rust library for building AI agents, inspired by Atomic Agents—with the same focus on staying small, modular, and easy to maintain without sacrificing developer experience.
- Modular pieces — agents, tools, and context stay separate so you can swap or extend one without untangling the rest.
- Structured I/O Types — define what you send and what you expect back in Rust; the model is guided to answer in that shape so you handle fields and values instead of parsing free-form text.
- Custom tools — run your own logic from the workflow, plus optional ready-made tools when you want them.
- Native Rust — lighter and faster than typical Python-based agent setups.
Example
use nano_agent::{
AgentConfig, BasicChatInputSchema, BasicNanoAgent, NanoAgent,
context::{ChatHistory, SystemPromptGenerator},
};
use schemars::JsonSchema;
use serde::{Deserialize, Serialize};
#[derive(Serialize, Deserialize, JsonSchema)]
struct CustomOutputSchema {
#[schemars(description = "The response to the user's question")]
chat_message: String,
#[schemars(description = "Suggested follow-up questions for the user")]
suggested_questions: Vec<String>,
}
#[tokio::main]
async fn main() {
let mut agent = BasicNanoAgent::<BasicChatInputSchema, CustomOutputSchema>::new(
AgentConfig::new("gemini-2.5-flash-lite")
.with_system_prompt_generator(
SystemPromptGenerator::new()
.with_background(vec![
"This assistant is knowledgeable, helpful, and suggests follow-up questions."
.to_string(),
])
.with_steps(vec![
"Analyze the user's input to understand the context and intent."
.to_string(),
"Formulate a relevant and informative response.".to_string(),
"Generate 3 suggested follow-up questions for the user.".to_string(),
])
.with_output_instructions(vec![
"Provide clear and concise information in response to user queries."
.to_string(),
"Conclude each response with 3 relevant suggested questions for the user."
.to_string(),
]),
)
.with_chat_history(ChatHistory::new()),
);
let response: CustomOutputSchema = match agent
.run(BasicChatInputSchema {
chat_message: "Tell me about the Nano Agent framework".to_string(),
})
.await
{
Ok(response) => response,
Err(error) => {
eprintln!("Agent error: {}", error);
return;
}
};
println!("Agent: {}", response.chat_message);
println!("Suggested questions:");
for question in response.suggested_questions {
println!("- {}", question);
}
}
To run this example, add the following dependencies to your Cargo.toml:
[dependencies]
nano-agent = "0.1"
schemars = "1.0"
serde = { version = "1", features = ["derive"] }
serde_json = { version = "1" }
tokio = { version = "1", features = ["full"] }
Status
