XP MCP Documentation — Public (anonymous)

# 1. Open a session. Server returns ``Mcp-Session-Id`` header.
curl -i -X POST http://mcp-store.xp.tickets/mcp \
  -H 'Content-Type: application/json' \
  -H 'Accept: application/json, text/event-stream' \
  -d '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"demo","version":"1.0"}}}'

# 2. List visible tools (open-world only).
curl -X POST http://mcp-store.xp.tickets/mcp \
  -H 'Content-Type: application/json' \
  -H 'Accept: application/json, text/event-stream' \
  -H "Mcp-Session-Id: $SESSION" \
  -d '{"jsonrpc":"2.0","id":2,"method":"tools/list"}'

# 3. Call an open-world tool. No bearer required.
curl -X POST http://mcp-store.xp.tickets/mcp \
  -H 'Content-Type: application/json' \
  -H 'Accept: application/json, text/event-stream' \
  -H "Mcp-Session-Id: $SESSION" \
  -d '{"jsonrpc":"2.0","id":3,"method":"tools/call","params":{"name":"search_events","arguments":{"query":"taylor swift"}}}'

# Turn 1 — preview (no wallet)
buy_tickets(event_id=<id>, uvid=<uvid>, quantity=<n>,
            confirm=False, rail="x402")
# → returns x402.accepts[0] (PaymentRequirements) + facilitators_available

# You sign accepts[0] locally with your own Solana wallet (see signer below).

# Turn 2 — settle (optionally pick a facilitator id from facilitators_available)
buy_tickets(event_id=<id>, uvid=<uvid>, quantity=<n>,
            confirm=True, rail="x402", payment_proof="<b64>",
            facilitator="payai")            # or another id from facilitators_available

// Inputs: accepts (= preview.x402.accepts[0]) + your Solana Keypair `buyer`.
// Output: base64 string → pass as `payment_proof` on the settle turn.
import {
  ComputeBudgetProgram, Connection, Keypair, PublicKey,
  TransactionMessage, VersionedTransaction,
} from "@solana/web3.js"
import {
  createTransferCheckedInstruction, getAssociatedTokenAddressSync,
} from "@solana/spl-token"

const conn = new Connection(SOLANA_RPC_URL, "confirmed")
const mint = new PublicKey(accepts.asset)
const payTo = new PublicKey(accepts.payTo)
const amount = BigInt(accepts.amount)        // micro-USDC, 6 decimals
const USDC_DECIMALS = 6

// Facilitator-sponsored fees: read feePayer from envelope. When present,
// buyer signs ONLY the transfer authority; facilitator co-signs gas at
// /settle. When absent (legacy buyer-pays-fees), buyer pays gas too.
const feePayer = new PublicKey(accepts.extra?.feePayer ?? buyer.publicKey)

const buyerAta = getAssociatedTokenAddressSync(mint, buyer.publicKey)
const payToAta = getAssociatedTokenAddressSync(mint, payTo)
// Pre-flight (recommended): assert buyer ATA balance ≥ amount, merchant ATA
// exists, and — only when buyer === feePayer — buyer has SOL for gas.

// Instructions MUST follow the x402 SVM exact order:
//   [ComputeBudget.setComputeUnitLimit, setComputeUnitPrice, TransferChecked].
// No ATA-create. Token-2022 is allowed by the spec but verify facilitator support.
const ix = [
  ComputeBudgetProgram.setComputeUnitLimit({ units: 20_000 }),
  ComputeBudgetProgram.setComputeUnitPrice({ microLamports: 1 }),
  createTransferCheckedInstruction(
    buyerAta, mint, payToAta, buyer.publicKey, amount, USDC_DECIMALS,
  ),
]

const { blockhash } = await conn.getLatestBlockhash("confirmed")
const msg = new TransactionMessage({
  payerKey: feePayer,                         // facilitator's pubkey when sponsored
  recentBlockhash: blockhash,
  instructions: ix,
}).compileToV0Message()

const tx = new VersionedTransaction(msg)
tx.sign([buyer])                              // partial sign — leave feePayer slot empty

const envelope = {
  x402Version: 2,
  scheme: accepts.scheme,
  network: accepts.network,
  payload: { transaction: Buffer.from(tx.serialize()).toString("base64") },
  accepted: accepts,
  extensions: {},
}
const payment_proof = Buffer.from(JSON.stringify(envelope), "utf-8").toString("base64")
// → pass payment_proof to buy_tickets(confirm=True, rail="x402", payment_proof, ...)