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Beauty & Personal Care · x402 · early usage

Atomically write (or release) a key only if its current value equals `expected` - the c…

Atomically write (or release) a key only if its current value equals `expected` - the coordination primitive for distributed locks and optimistic concurrency across agents. Acquire a lock: expected=null + a value + ttlSeconds. Release it: expected=<your token…

by agent402.tools · discovered, not yet claimed by its owner · updated 2026-10-08

30d calls4
30d payers4
MethodPOST
Outputjson

Mirrored from Coinbase's public x402 Bazaar. The description is the provider's own text and has not been reviewed here; the payment requirements are copied as published.

What it does

Atomically write (or release) a key only if its current value equals `expected` - the coordination primitive for distributed locks and optimistic concurrency across agents. Acquire a lock: expected=null + a value + ttlSeconds. Release it: expected=<your token> with no value (deletes on match). Update safely: expected=<old>, value=<new>. Returns whether it swapped and the current value.

Tags: memory · cas · compare-and-set · lock · coordination · bazaar · builder-code · payment-identifier

Call contract

Method
POST
Input
json
Output
json
Last paid call
2026-10-08
Input example from Bazaar metadata
{
  "expected": null,
  "key": "locks/import",
  "ttlSeconds": 30,
  "value": "agent-7"
}
Output example
{
  "expiresAt": 1760086430,
  "key": "locks/import",
  "owner": "0x…",
  "swapped": true,
  "value": "agent-7"
}

Use with an agent

  1. Discover. Agents find this listing with GET https://bazaar.saylorinnovations.com/discovery/search?query=…, the MCP tool search_resources, or /discovery/resources.
  2. Inspect. Fetch /resources/27937.json for the price and payment options.
  3. Pay. Call GET https://agent402.tools/api/memory/cas. The provider answers 402 with its payment requirements. An x402 client signs one of the options below and retries with PAYMENT-SIGNATURE.
  4. Execute. The provider returns 200 with the data. Agent Bazaar is not in the request path and never sees your payment.

For humans

You don't need an account or an API key; you need a wallet holding a small amount of USDC on Base, Polygon, Arbitrum One, eip155:143, Avalanche, eip155:1329, Optimism, eip155:4663, eip155:42220, and an x402-capable client (see the examples below). Call the endpoint unpaid first to see exactly what it asks for.

Pricing & payment

Price
$0.001 / request
Protocol
x402 v2
Auth
No account or API key. Pay per request.
Networks
Base, Polygon, Arbitrum One, eip155:143, Avalanche, eip155:1329, Optimism, eip155:4663, eip155:42220
Demand
4 calls · 4 unique payers in 30d (public x402 Bazaar data)

x402 payment requirements

SchemeNetworkAssetAmountPay toTimeout
exactBase
eip155:8453		USDC$0.0010xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0300s
exactPolygon
eip155:137		USDC$0.0010xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0300s
exactArbitrum One
eip155:42161		USDC$0.0010xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0300s
exacteip155:143
eip155:143		0x754704Bc059F8C67012fEd69BC8A327a5aafb60310000xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0300s
exactAvalanche
eip155:43114		0xB97EF9Ef8734C71904D8002F8b6Bc66Dd9c48a6E10000xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0300s
exacteip155:1329
eip155:1329		0xe15fC38F6D8c56aF07bbCBe3BAf5708A2Bf4239210000xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0300s
exactOptimism
eip155:10		0x0b2C639c533813f4Aa9D7837CAf62653d097Ff8520000xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0300s
exacteip155:4663
eip155:4663		0x5fc5360D0400a0Fd4f2af552ADD042D716F1d16810000xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0300s
exacteip155:42220
eip155:42220		0xcebA9300f2b948710d2653dD7B07f33A8B32118C10000xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0300s
accepts[] (raw JSON)
[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "payTo": "0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "1000",
    "amountUsd": 0.001,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:137",
    "payTo": "0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0",
    "asset": "0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359",
    "amount": "1000",
    "amountUsd": 0.001,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:42161",
    "payTo": "0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0",
    "asset": "0xaf88d065e77c8cC2239327C5EDb3A432268e5831",
    "amount": "1000",
    "amountUsd": 0.001,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:143",
    "payTo": "0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0",
    "asset": "0x754704Bc059F8C67012fEd69BC8A327a5aafb603",
    "amount": "1000",
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:43114",
    "payTo": "0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0",
    "asset": "0xB97EF9Ef8734C71904D8002F8b6Bc66Dd9c48a6E",
    "amount": "1000",
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:1329",
    "payTo": "0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0",
    "asset": "0xe15fC38F6D8c56aF07bbCBe3BAf5708A2Bf42392",
    "amount": "1000",
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:10",
    "payTo": "0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0",
    "asset": "0x0b2C639c533813f4Aa9D7837CAf62653d097Ff85",
    "amount": "2000",
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:4663",
    "payTo": "0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0",
    "asset": "0x5fc5360D0400a0Fd4f2af552ADD042D716F1d168",
    "amount": "1000",
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:42220",
    "payTo": "0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0",
    "asset": "0xcebA9300f2b948710d2653dD7B07f33A8B32118C",
    "amount": "1000",
    "maxTimeoutSeconds": 300
  }
]

Schemas

Output schema (JSON Schema)
{
  "properties": {
    "example": {
      "properties": {
        "expiresAt": {
          "type": "integer"
        },
        "key": {
          "type": "string"
        },
        "owner": {
          "type": "string"
        },
        "swapped": {
          "type": "boolean"
        },
        "value": {
          "type": "string"
        }
      },
      "required": [
        "key",
        "swapped",
        "value",
        "owner",
        "expiresAt"
      ],
      "type": "object"
    },
    "type": {
      "type": "string"
    }
  },
  "required": [
    "type"
  ],
  "type": "object"
}
Example shape — generated from the schema, not a captured live response
{
  "example": {
    "expiresAt": 0,
    "key": "string",
    "owner": "string",
    "swapped": true,
    "value": "string"
  },
  "type": "string"
}

Examples

curl
curl -X POST 'https://agent402.tools/api/memory/cas' -H 'Content-Type: application/json' --data '{"expected":null,"key":"locks/import","ttlSeconds":30,"value":"agent-7"}'
# -> 402 Payment Required; read PAYMENT-REQUIRED
# retry the identical request with PAYMENT-SIGNATURE
JavaScript
const res = await fetch("https://agent402.tools/api/memory/cas", {
  "method": "POST",
  "headers": {
    "content-type": "application/json"
  },
  "body": "{\"expected\":null,\"key\":\"locks/import\",\"ttlSeconds\":30,\"value\":\"agent-7\"}"
});
if (res.status === 402) {
  const { accepts } = await res.json();
  // pay one of accepts[] via an x402 client, then retry with the payment header
}
Python
import httpx
import json
res = httpx.request("POST", "https://agent402.tools/api/memory/cas", json=json.loads("{\"expected\":null,\"key\":\"locks/import\",\"ttlSeconds\":30,\"value\":\"agent-7\"}"))
if res.status_code == 402:
    accepts = res.json()["accepts"]
    # pay one of accepts[] via an x402 client, then retry with the payment header

Details

Provider
agent402.tools
Endpoint
https://agent402.tools/api/memory/cas
Machine-readable
/resources/27937.json