Cryptographic receipts for AI outputs on Base or Solana via x402.
If you already use X402, the x402 mcp server is the piece that lets your assistant work with it directly. Cryptographic receipts for AI outputs on Base or Solana via x402.
Every AI output is just text. There's no proof a specific model produced a specific response at a specific time — and as agents start hiring other agents, that trust gap gets expensive. x402 Notary closes it: submit any inference, pay $0.001 in USDC (automatic, via x402 on Base or Solana — no API key, no account), and get back a signed, timestamped, chain-anchored receipt that anyone can verify, free, forever.
The toolset is worth reading before you wire it up, because it tells you what the integration is really for:
notarize_inference — $0.001notarize_batch — $0.005verify_attestation — freeget_receipt — freenotary_stats — freenotary_pubkey — freeSetup follows the usual MCP pattern — install or clone the server, register it in your client's configuration file, restart the client. The configuration blocks on this page cover the common clients.
Configuration is passed through the environment: WALLET_PRIVATE_KEY, NOTARY_RAIL, NOTARY_BASE_URL, SOLANA_PRIVATE_KEY. Treat anything key-shaped as a real credential — scope it to the minimum the server needs, and rotate it if it ever lands in a shared config.
Among the developer tooling options, the useful question is rarely "what can it do" but "what does it cost you to run" — permissions, credentials, and how much of your context its toolset consumes. X402's toolset — notarize_inference, notarize_batch, verify_attestation and 3 more — is a fair guide to whether it matches your workflow. It is maintained by forgemeshlabs; worth a glance at recent repository activity before you build anything load-bearing on it.
SyncDev reviews every entry in this directory against the project's own documentation before publishing, and revisits them as servers change.
| Tool | What it does |
|---|---|
| notarize_inference | $0.001 |
| notarize_batch | $0.005 |
| verify_attestation | **free** |
| get_receipt | **free** |
| notary_stats | **free** |
| notary_pubkey | **free** |
{
"mcpServers": {
"x402-notary": {
"command": "npx",
"args": ["-y", "@forgemeshlabs/x402-notary-mcp"],
"env": {
"WALLET_PRIVATE_KEY": "0x..."
}
}
}
}Configuration as documented by the project. Restart the client after saving.
| Variable | Description | Required |
|---|---|---|
| WALLET_PRIVATE_KEY | Credential the server authenticates with. | Yes |
| NOTARY_RAIL | Configuration value read at startup. | Optional |
| NOTARY_BASE_URL | Endpoint or connection string the server talks to. | Yes |
| SOLANA_PRIVATE_KEY | Credential the server authenticates with. | Yes |
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