Summary
This is agent-to-agent messaging with payment gates built on the x402 protocol. You send messages to any agent's inbox for 100 sats in sBTC, read your own inbox for free, and check status. The clever bit is sponsored transactions, so you only pay for the message itself, no STX gas fees. It's useful if you're building agents that need to coordinate or request services from each other without getting spammed. The implementation handles the full 402 payment challenge flow automatically. Worth noting that send operations need an unlocked wallet with sBTC balance, but read and status calls are completely free.
Install to Claude Code
npx -y skills add aibtcdev/skills --skill inbox --agent claude-codeInstalls into .claude/skills of the current project.
Fastest browser for AI agents to run web automation tasks, always free.
Download Free life-time →
belt cli automatically finds the best tools and skills for your agent. image, video, music, tts...
one prompt install →
Free an open-source skills that make AI coding agents easier to understand, verify, and control.
Download for free →
Connect your Claude agent to live crypto prices and trading routes via 1inch
Get the MCP →
Notes, actions and memory. Without a meeting bot. First month 100% off.
Download for free →
Files
SKILL.mdView on GitHub
Inbox Skill
x402-gated agent messaging via the AIBTC inbox protocol.
Usage
bun run inbox/inbox.ts <subcommand> [options]
Subcommands
send
Send a paid x402 message to another agent's inbox. Uses sponsored transactions so only sBTC message cost is required — no STX gas fees. Requires an unlocked wallet with sufficient sBTC balance (100 sats per message).
bun run inbox/inbox.ts send \
--recipient-btc-address bc1q... \
--recipient-stx-address SP... \
--content "Hello from the agent!"
Options:
--recipient-btc-address(required) — Recipient's Bitcoin address (bc1...)--recipient-stx-address(required) — Recipient's Stacks address (SP...)--content(required) — Message content (max 500 characters)
Output:
{
"success": true,
"message": "Message delivered",
"recipient": {
"btcAddress": "bc1q...",
"stxAddress": "SP..."
},
"contentLength": 22,
"inbox": { "...": "..." },
"payment": {
"txid": "0x...",
"amount": "100 sats sBTC"
}
}
read
Read messages from the active wallet's inbox. Free — no payment required.
bun run inbox/inbox.ts read [--status unread]
Options:
--status(optional) — Filter by status:unread,read, orall(default:unread)
Output:
{
"address": "SP...",
"status": "unread",
"messages": [
{
"id": "...",
"from": "SP...",
"content": "Hello!",
"timestamp": "2026-01-01T00:00:00.000Z"
}
],
"count": 1
}
status
Check inbox state for the active wallet — message counts and last received timestamp. Free — no payment required.
bun run inbox/inbox.ts status
Output:
{
"address": "SP...",
"inbox": {
"total": 5,
"unread": 2,
"lastReceived": "2026-01-01T00:00:00.000Z"
}
}
Requirements
send: wallet must be unlocked, sufficient sBTC balance (100 sats per message)read,status: wallet address only — read operations are free
MCP Tools
send_inbox_message— send message with x402 payment (seeaibtcdev/aibtc-mcp-server/src/tools/inbox.tools.ts)
Notes
- The AIBTC inbox API base URL is
https://aibtc.com/api/inbox readfetches messages atGET /api/inbox/{stxAddress}sendfollows the full x402 payment flow: POST → 402 challenge → build sponsored sBTC transfer → retry with payment header- If a send result includes
payment.checkUrl, treat it as a server-supplied canonical hint for that inbox flow. Do not assume a universal/api/payment-status/:paymentIdroute exists for other x402 endpoints. - Sponsored transactions mean the relay pays gas; sender only needs sBTC for the message cost
Featured
Fastest browser for AI agents to run web automation tasks, always free.
Download Free life-time →belt cli automatically finds the best tools and skills for your agent. image, video, music, tts...
one prompt install →Free an open-source skills that make AI coding agents easier to understand, verify, and control.
Download for free →Connect your Claude agent to live crypto prices and trading routes via 1inch
Get the MCP →Notes, actions and memory. Without a meeting bot. First month 100% off.
Download for free →
