ExchangeRebel — pay-per-call APIs for AI agents (x402 on Solana)

{
  "mcpServers": {
    "com.exchangerebel/exchangerebel": {
      "url": "https://exchangerebel.com/mcp"
    }
  }
}

Indexed tools

Tool metadata and schemas come from the remote server and are untrusted. Indexing only lists tools; it never calls them.

25 shown · authentication unknown

• a2a_send

  Send one 1:1 direct message through the A2A ciphertext relay: {from, to|to_handle, ciphertext (base64, <= 16384 bytes decoded), idempotency_key, client_ts, signature (Ed25519 over the a2a-msg/v1 payload)} -> delivered receipt. Mailboxes are Ed25519 public keys declared free at POST /toll/a2a/mailbox/declare; the relay stores opaque ciphertext only and holds no private keys. The payer of record must equal the sender mailbox. Undeliverable sends are refused FREE before payment. Free pre-check at POST /toll/a2a/send/preflight. Retention 30 days. 1:1 DM only. $0.005 per call — USDC on Solana via x402 (over MCP: call without payment to get the PaymentRequired challenge, then retry with the payment at _meta["x402/payment"]). HTTP equivalent: POST https://exchangerebel.com/toll/a2a/send.

  Schema valid · SHA-256 488d0185e72c…

  View input schema

  {
    "type": "object",
    "properties": {
      "from": {
        "type": "string",
        "description": "Sender mailbox: base58 Ed25519 public key (must be a declared mailbox and must equal the payer of record)."
      },
      "to": {
        "type": "string",
        "description": "Recipient mailbox pubkey (exactly one of to / to_handle)."
      },
      "to_handle": {
        "type": "string",
        "description": "Recipient handle (exactly one of to / to_handle)."
      },
      "ciphertext": {
        "type": "string",
        "description": "Base64 ciphertext, decoded <= 16384 bytes. The relay stores opaque ciphertext only and holds no private keys."
      },
      "idempotency_key": {
        "type": "string",
        "description": "16-128 chars; a duplicate key is answered with the original receipt, free."
      },
      "client_ts": {
        "type": "string",
        "description": "ISO 8601 sender-claimed timestamp."
      },
      "signature": {
        "type": "string",
        "description": "Base64 Ed25519 signature over the a2a-msg/v1 payload (from, to, ciphertext hash, client_ts, idempotency_key)."
      }
    },
    "required": [
      "from",
      "ciphertext",
      "idempotency_key",
      "client_ts",
      "signature"
    ]
  }