Agent Cantina

"Keep your Agents fed with prompts!"

What is Agent Cantina?

Agent Cantina is a TUI tool for Elastic Agent Builder developers.

With it, you can:

• Load, edit and save a series of individual prompts from a PROMPTS.md file.
• Run an automatic chat session against an Agent with the prompts in your PROMPTS.md file - no more manually chatting with an agent to verify something works!
• View all existing Agents in the Kibana instance, and create brand new ones with assigned tools.

Who is this tool for?

This tool is for developers who require repeatable chat sessions while developing or modifying:

• Custom Agents
• Tools
• Workflows

How to get started

You can download a Mac-compatible binary under the Releases page.

Agent Cantina requires your Kibana URL and API key to be set as environment variables.

export KIBANA_URL=<your-kibana-url>
export ES_HOST=<your-elasticsearch-url> # optional, only necessary if you want to index chat sessions
export API_KEY=<your-api-key>

# alternatively, you can create an .env file and Agent Cantina will pick up the environment variables from there

cat > .env <<'EOF'
KIBANA_URL=<your-kibana-url>
ES_HOST=<your-elasticsearch-url>
API_KEY=<your-api-key>
EOF

./agent_cantina

Kibana HTTPS / self-signed certs (local dev)

If you start Kibana locally with --ssl, it typically uses a self-signed certificate (and may have a hostname like CN=kibana while you connect to https://localhost:5601). In that case, Agent Cantina may fail to connect unless your OS trusts the certificate.

For local development only, you can bypass TLS verification:

export KIBANA_INSECURE_TLS=1

Tutorial

There are three "panels" in Agent Cantina:

• Prompts
• Agents
• Conversation

Each panel serves a specific purpose, and has its own set of unique actions.

You can cycle through the current "active" panel with the Tab key.

The Prompts panel and PROMPTS.md

---

This is where you can view and edit your PROMPTS.md file. If no PROMPTS.md is present, Agent Cantina will create a basic one for you and load it.

A note on formatting - PROMPTS.md needs to follow a very specific format:

## Prompt 1

<your-first-prompt-here>

## Prompt 2

<your-second-prompt-here>

etc...

Special actions available in the Prompts panel:

• Ctrl-S: Save any edits to PROMPTS.md
• Ctrl-R: Reload the PROMPTS.md from disk

The Agents panel

---

This is where you can select an Agent to send your prompts to.

All agents that are configured in Agent Builder will appear here. Use the Up/Down arrows to choose an Agent, and Enter to begin a chat session with it.

Special actions available in the Agents panel:

• n: Create a brand new Agent
• e: Edit an existing Agent
• d: Delete an existing Agent
• Ctrl-R: Reload the list of agents from Agent Builder

Creating a brand-new agent from within Agent Cantina

You can create a new agent by hitting n in the Agents panel. This will open a new popup window with two tabs, Prompt and Tools.

In the Prompt tab, you can set:

• Name
• Description (optional)
• Instructions / prompt

Use the Tab key to switch between each field in the Prompt tab.

Use the Left/Right arrows to switch between the Prompt and Tools tabs. In the Tools tab, use the Up/Down and Enter keys to select which tools the Agent should be configured with.

When you are done configuring your agent, use Ctrl-S to create your Agent!

Once you Agent has been created, you can go back and edit it by hitting e from within the Agents panel.

The Conversation panel

---

This is where you can see the chat session prompts and responses, as well as system messages.

Special actions available in the Conversations panel:

• r: Re-run the chat session (good if you make edits to your PROMPTS.md and need to try again)
• End: Go to the bottom of the chat window (latest message)
• Ctrl-S: Dump the entire chat history into a Markdown file (written to the current working directory)
• i: Index your chat history into an Elasticsearch index

When indexing your chat history, you will see the index name and document ID in the conversation history window:

Building from source

Prior to building, make sure you have Rust installed. This application was developed with rustc 1.91.0. It may build with older versions, but I haven't tested this.

make build # for debug builds
make build-release # for release builds

Testing

cargo test

Snapshot tests use insta. To (re)generate snapshots:

INSTA_UPDATE=always cargo test

If you prefer the cargo-insta workflow, install it and accept snapshots:

cargo install cargo-insta
cargo insta accept

FAQ

• Question: Every chat run I perform creates a new chat session in Agent Builder. Is there any way I can add new prompts and resume an existing chat session?

  • Answer: Not at this time. This is an improvement I'd like to make!

• Question: Editing my PROMPTS.md in the editing window is kinda slow!

  • Answer: Yeah, it's good for small edits and tweaks, but you probably shouldn't write the entire thing there. That's what Ctrl+R is for - you can make edits in your own text editor, save it, then reload the PROMPTS.md file!

• Question: The color theme doesn't look good on my particular terminal?

  • Answer: The theme is based on Elastic's colorway, and is defined in theme.rs. You can always change it up to suit your particular terminal or preferences! You'll have to re-build the executable, though. This may turn into a YAML file or something later, who knows?

• Question: Was this vibecoded?

  • Answer: 100%. As an enthusiast of the Rust language, I really wanted to write this one by hand, but I just don't have enough hours in the day to write tooling on top of feature work :(

Feature wishlist/To-dos (in no particular order)

• Possibly improve the PROMPTS.md required formatting to be less verbose
• When dumping to markdown, it should save to a configurable directory
• Ability to load different Markdown files via a file browser-type interface
• Implement some basic error logging
• Track conversation IDs so certain conversations can be resumed, even after Agent Cantina is exited and started again