Build Your First Agent
:::info ~5 min
Prerequisite: completed Quickstart — ~/.ethos/config.yaml exists.
:::
Start a session
make dev
Ethos opens an interactive chat session. You'll see:
ethos v0.x.x · researcher · claude-opus-4-7
Type a message or /help for commands.
>
The header shows: current version, active personality, and model.
Send a message
Type any message and press Enter. Responses stream in real-time:
> What's the capital of France?
Paris is the capital of France. It has served as the country's capital
since...
While the model is responding, tool calls appear inline:
> Search the web for the latest TypeScript release
[web_search] searching...
[web_search] ✓ 340ms
TypeScript 6.0 was released...
Check token usage
After a few messages, run:
/usage
Output:
Session usage
Input tokens: 2,847
Output tokens: 512
Estimated cost: $0.0041
Start a fresh session
/new
This creates a new session. History from the previous session is preserved in SQLite — you can reference it in future sessions but the model won't see it immediately.
Observe session persistence
Exit with Ctrl+C, then run make dev again. Send:
> What was the last thing we discussed?
The agent remembers — sessions persist in ~/.ethos/sessions.db across restarts. Each working directory gets its own session history (the session key is cli:<directory-name>).
All slash commands
/personality list list available personalities
/personality <id> switch personality
/memory show MEMORY.md and USER.md
/usage token and cost stats for this session
/new start a fresh session
/help show all commands