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 addressdiscord- Discord usernamewebhook- HTTP endpoint for structured messagessignal- Signal phone numbertelegram- 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-cardvCard extension: Look for
X-AGENT-CARDfield in contact cardsAsk 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.