Overview

Agents in Archestra provide a comprehensive no-code solution for building autonomous and semi-autonomous agents that can access your data and work together in swarms. Each agent consists of a User Prompt, System Prompt, assigned tools, and sub-agents, and can be triggered via:

• Archestra Chat UI
• A2A (Agent-to-Agent) protocol
• Scheduled Tasks
• Incoming Email
• Slack
• MS Teams

Trigger setup is managed from Agent Triggers. Slack, MS Teams, and Incoming Email each have their own setup flow, and Incoming Email also owns the per-agent email invocation settings.

A2A (Agent-to-Agent)

A2A is a JSON-RPC 2.0 gateway that allows external systems to invoke agents programmatically. Each Prompt exposes two endpoints:

• Agent Card Discovery: GET /v1/a2a/:promptId/.well-known/agent.json
• Message Execution: POST /v1/a2a/:promptId

Authentication

All A2A requests require Bearer token authentication. Generate tokens via the Profile's API key settings or use team tokens for organization-wide access.

Agent Card

The discovery endpoint returns an AgentCard describing the agent's capabilities:

{
  "name": "My Agent",
  "description": "Agent description from prompt",
  "version": "1.0.0",
  "capabilities": {
    "streaming": false,
    "pushNotifications": false
  },
  "defaultInputModes": ["text"],
  "defaultOutputModes": ["text"],
  "skills": [{ "id": "default", "name": "Default Skill" }]
}

Sending Messages

Send JSON-RPC 2.0 requests to execute the agent:

curl -X POST "https://api.example.com/v1/a2a/<promptId>" \
  -H "Authorization: Bearer <token>" \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "id": "1",
    "method": "message/send",
    "params": {
      "message": {
        "parts": [{ "kind": "text", "text": "Hello agent!" }]
      }
    }
  }'

Response:

{
  "jsonrpc": "2.0",
  "id": "1",
  "result": {
    "messageId": "msg-...",
    "role": "agent",
    "parts": [{ "kind": "text", "text": "Agent response..." }]
  }
}

Delegation Chain

A2A supports nested agent-to-agent calls. When one agent invokes another, the delegation chain tracks the call path for observability. This enables multi-step agent workflows where agents can use other agents as tools.

Delegated sub-agents also inherit the current tool guardrails trust state. If the parent agent has already crossed a sensitive-context boundary, the child starts in that same unsafe state, so downstream tool call policies continue to enforce the stricter rules instead of resetting during delegation.

Configuration

A2A uses the same LLM configuration as Chat. See Deployment - Environment Variables for the full list of ARCHESTRA_CHAT_* variables.

System Prompt Templating

Agent system prompts support Handlebars templating. Templates are rendered at runtime before the prompt is sent to the LLM, with the current user's context injected as variables.

Variables

Helpers

All built-in Handlebars helpers (#each, #if, #with, #unless) are also available, along with Archestra helpers like includes, equals, contains, and json.

Example

You are a helpful assistant for
{{user.name}}. Today's date is
{{currentDate}}.

{{#includes user.teams "Engineering"}}
  You have access to engineering-specific tools and documentation.
{{/includes}}

{{#if user.teams}}
  The user belongs to:
  {{#each user.teams}}{{this}}{{#unless @last}}, {{/unless}}{{/each}}.
{{/if}}