Memory counter

Atomically increment (or decrement) a numeric key and return the new value - a coordination primitive for counters, locks, and rate budgets shared across agents. Send POST /api/memory/incr with the required field key and pay $0.001 per call over x402 with USDC on an EVM chain (the paying wallet is the identity). It returns a JSON object with key, value and owner.

Creates the key at 0 if absent. Retry safely with a requestId: a repeat with the same id returns the first answer and counts once; a retry without one counts again.

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Parameters

Example request

curl -i -X POST https://agent402.tools/api/memory/incr \
  -H "Content-Type: application/json" \
  -d '{"key":"jobs/processed","by":1}'

Without payment this returns HTTP 402 Payment Required with the exact price for memory-incr; any x402 v2 or MPP client pays it and retries.

Example response

{
  "key": "jobs/processed",
  "value": 43,
  "owner": "0x…"
}

From an MCP client

catalog.call {
  "slug": "memory-incr",
  "params": {
    "key": "jobs/processed",
    "by": 1
  }
}

The hosted connector at https://agent402.tools/mcp needs a payment for memory-incr; the stdio package pays it from a wallet. Local install: npx -y agent402-mcp.

Errors and behavior

• key is required. An input the tool rejects returns an HTTP 4xx whose body carries error, tool, expected, required and example, so the caller can correct it.
• A paid call that ends in any status of 400 or above is not charged over x402 or MPP: settlement is canceled when the tool fails.
• Wallet-only: this tool reaches the network or stored state, so it has no proof-of-work tier.
• Identity-bound: results are keyed to the wallet that signed the payment, so only EVM x402 payments are accepted; credits keys and Tempo are refused.
• A GET or HEAD to /api/memory/incr returns the same 402 quote, so the price can be read without a body.
• An Idempotency-Key header makes a retried paid call replay the first 200 instead of charging again (an answer larger than 1 MB is not replayed).

Paid call (JavaScript agent)

import { wrapFetchWithPayment } from "@x402/fetch";
import { x402Client } from "@x402/core/client";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

const client = new x402Client();
client.setSpendControls?.({ maxAmountPerPayment: "$0.001" }); // refuse any quote above this tool's price
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/memory/incr", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "key": "jobs/processed",
    "by": 1
  }),
});

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