Memory recall

Recall remembered text by similarity to a query (ranked by cosine similarity), not by exact key. Send POST /api/memory/recall with the required field query and pay $0.002 per call over x402 with USDC on an EVM chain (the paying wallet is the identity). It returns a JSON object with query and results.

Returns the top-k matches with scores. The retrieval half of the wallet-scoped semantic memory.

Category: Agent memory & coordination · Tags: memory semantic search recall vector similarity

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Parameters

Example request

curl -i -X POST https://agent402.tools/api/memory/recall \
  -H "Content-Type: application/json" \
  -d '{"query":"why did the deployment break","k":3}'

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

Example response

{
  "query": "why did the deployment break",
  "results": [
    {
      "id": "abc123",
      "score": 0.62,
      "text": "The deploy failed because…"
    }
  ]
}

From an MCP client

catalog.call {
  "slug": "memory-recall",
  "params": {
    "query": "why did the deployment break",
    "k": 3
  }
}

The hosted connector at https://agent402.tools/mcp needs a payment for memory-recall; the stdio package pays it from a wallet or from AGENT402_CREDITS_KEY (wallet only for this tool). Local install: npx -y agent402-mcp.

Errors and behavior

• query 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 cancelled 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/recall 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?.(false); // keep your own spending ceiling in code
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/memory/recall", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "query": "why did the deployment break",
    "k": 3
  }),
});

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