Every new standard, spoken at your door.
New agent standards keep arriving. Sill speaks the ones agents use today, on your own domain. You never have to learn the acronyms.
What agents can do here.
Direct tool line
Model Context Protocol
version 2025-06-18
A direct line agents use to call your skills, like Get pricing or Browse catalog. Every call is recorded.
Live
Agent card
Agent-to-Agent
version a2a/1.2
A signed business card for AI agents that lists what you offer. Agents read it to find your skills, then call them.
Live · agent card only; agents call skills over MCP
Signed permission
Agent Payments Protocol
An agent's signed payment request is checked against your rules before anything is charged.
Live · signed mandates checked at your door
Signed catalog
Agentic Resource Discovery
version 1.0
A signed catalog of what you offer. Agents use it to understand your offer without reading your website.
Live
Plain summary for models
llms.txt
A plain summary of your business that language models read.
Live
HTML gateway
HTML agent gateway (/agent)
A page agents that read HTML, rather than JSON, can arrive at.
Live
Public verification keys
Public signing keys
The ed25519 keys anyone can use to verify Sill signatures.
Live
Checkout endpoint
Universal Commerce Protocol
version 2026-08-25
Agent platforms can run a signed checkout against your store. Available on sites with Stripe connected.
Live · checkout and orders on a connected Stripe account
Signature checks
Signed agent requests (RFC 9421)
version draft-ietf-webbotauth-httpsig-protocol-00
On Cloudflare Worker and WordPress installs, Sill checks the signature of agents that sign their requests and marks them verified.
Live · on Cloudflare Worker and WordPress installs
Checkout and signed permissions run on your connected Stripe account. Sill never holds funds. Verification keys and the hosted verifier live on the trust page.