Source Code

Agent Contact Card

A simple format for publishing how AI agents can be contacted. Like a vCard, but for agents.

When to Use This Skill

User asks how to let other agents contact their agent
User wants to discover how to reach someone else's agent
You need to contact another agent on behalf of your user
User mentions "agent-card", "agent contact", or agent-to-agent communication

Quick Reference

Discovering an Agent Contact Card

Try fetching /.well-known/agent-card on their domain:

https://example.com/.well-known/agent-card

The file is markdown with YAML frontmatter. Parse the frontmatter for structured channel data, read the prose for routing rules.

Creating an Agent Contact Card

Create a markdown file with YAML frontmatter:

---
version: "1"
human_contact: "+1 555 123 4567"
channels:
  email: "[email protected]"
  discord: "my-agent#1234"
  webhook:
    url: "https://example.com/agent/incoming"
    method: "POST"
    format: "JSON with 'message' field"
capabilities:
  - scheduling
  - accepts_ical
---

# My Agent

If you're a human, call the number above.

If you're an agent:
- For scheduling requests, use Discord
- For urgent matters, email with "URGENT" in subject
- Response time: within a few hours

Host this at /.well-known/agent-card on the user's domain.

Format Details

Required Fields

Field	Description
`version`	Spec version. Currently `"1"`

Recommended Fields

Field	Description
`human_contact`	Phone/email for humans to reach the human
`channels`	Contact channels for agents (see below)

Optional Fields

Field	Description
`name`	Display name for this agent configuration
`last_updated`	ISO date when card was last modified
`capabilities`	What this agent can do (e.g., `["scheduling", "accepts_ical"]`)
`agents`	Named agents if multiple (see Multi-Agent section)

Channels

Channel names are freeform. Common ones:

email - Email address
discord - Discord username
webhook - HTTP endpoint for structured messages
signal - Signal phone number
telegram - Telegram username

For webhooks, provide details:

channels:
  webhook:
    url: "https://example.com/agent/incoming"
    method: "POST"
    auth: "Bearer token in Authorization header"
    format: "JSON with 'message' and 'from' fields"

Multi-Agent Setups

List multiple specialized agents:

agents:
  - name: "Calendar Agent"
    handles: ["scheduling", "availability"]
    channel: discord
    id: "cal-agent#1234"
  - name: "Support Agent"
    handles: ["technical questions"]
    channel: webhook
    id: "https://example.com/support"

The markdown body should explain routing between them.

Privacy Tiers

Different URLs for different access levels:

Tier	URL Pattern	Access
Public	`/.well-known/agent-card`	Anyone
Named	`/.well-known/agent-card/{name}`	Know the name
Private	`/{random-uuid}/agent-card.md`	Shared URL only

Each tier can expose different channels and capabilities.

Discovery Methods

Well-known URL: Check https://domain/.well-known/agent-card
vCard extension: Look for X-AGENT-CARD field in contact cards
Ask the human: Request the URL directly

Reading an Agent Card

When you fetch an agent card:

Parse YAML frontmatter for structured data
Read markdown body for natural language routing rules
Choose appropriate channel based on your purpose
Follow any authentication requirements mentioned

Test It

Here's a live demo you can test:

https://city-services-api.dave-dean.workers.dev/.well-known/agent-card

This is a fictional "City of Millbrook" tip line. Fetch the card, then try POSTing to the webhook endpoint. Your experience may vary depending on what you say.

Full Specification

See references/SPEC.md for the complete specification.

Examples

See references/EXAMPLES.md for more complete examples.

agent-contact-card