modbender 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: "agent@example.com"
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-card - vCard extension: Look for
X-AGENT-CARDfield 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.