lettactl

kubectl-style CLI for managing Letta AI agent fleets declaratively.

When to Use

• Deploying multiple agents with shared configurations
• Managing agent memory blocks, tools, and folders
• Applying templates to existing agents
• Programmatic fleet management via SDK

Core Workflow

1. Define agents in fleet.yaml
2. Apply with lettactl apply -f fleet.yaml
3. Verify with lettactl get agents and lettactl describe agent <name>

Fleet YAML Structure

shared_blocks:
  - name: company-context
    description: Shared company knowledge
    limit: 5000
    from_file: ./context/company.md

agents:
  - name: support-agent
    description: Customer support assistant
    system_prompt:
      from_file: ./prompts/support.md
    llm_config:
      model: gpt-4o
      context_window: 128000
    memory_blocks:
      - name: persona
        description: Agent personality
        limit: 2000
        value: "You are a helpful support agent."
    shared_blocks:
      - company-context
    tools:
      - send_email
      - search_docs

See reference/fleet-config.md for full schema.

CLI Commands

Apply Configuration

lettactl apply -f fleet.yaml              # Create/update agents
lettactl apply -f fleet.yaml --dry-run    # Preview changes
lettactl apply -f fleet.yaml --match "*-draper"  # Template mode

Inspect Resources

lettactl get agents                    # List all agents
lettactl get agents -o wide            # With details
lettactl get blocks --shared           # Shared blocks only
lettactl get tools --orphaned          # Unused tools
lettactl describe agent <name>         # Full agent details

Messaging

lettactl send <agent> "Hello"          # Send message
lettactl send <agent> "Hi" --stream    # Stream response
lettactl messages list <agent>         # View history
lettactl messages reset <agent>        # Clear history

Observability

lettactl health                        # Server connectivity
lettactl files <agent>                 # Attached files
lettactl context <agent>               # Context window usage

See reference/cli-commands.md for all options.

Template Mode

Apply configuration to existing agents matching a pattern:

lettactl apply -f template.yaml --match "*-draper"

Uses three-way merge: preserves user-added resources while updating managed ones. See reference/template-mode.md.

SDK Usage

import { LettaCtl } from 'lettactl';

const ctl = new LettaCtl({ lettaBaseUrl: 'http://localhost:8283' });

await ctl.deployFromYaml('./fleet.yaml');
await ctl.deployFromYaml('./template.yaml', { match: '*-prod' });

See reference/sdk-usage.md for full API and reference/cli-commands.md for environment variables.