tereno-mcp

🛡️ Check before you act — an MCP server for Base, over x402

Ask what it costs before you pay for it. Free catalog, pricing and receipt tools work with no wallet and no signup; paid answers settle per call in USDC, and reusing an answer another agent already paid for costs less.

npx -y tereno-mcp

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⚡ Why this exists

An agent that reads a contract, signs a transaction or scrapes a page is acting on information it cannot verify. Most tools answer what something is. None of them tell you how long that answer stays true.

tereno-mcp puts Tereno inside any MCP client. Every paid answer comes back with the evidence behind it, the limits of that evidence, and the block it stops being valid at.

• No API key, no signup. The agent's wallet is the identity.
• Price before payment. tereno_price tells you the cost and whether the answer already exists, without a wallet and without committing to anything.
• Cheaper when shared. Deterministic answers are reused across agents: the first caller pays to compute, everyone after pays the reuse price.

🚀 Install

Add it to any MCP client — Claude Desktop, Claude Code, Cursor, Cline, Windsurf:

{
  "mcpServers": {
    "tereno": {
      "command": "npx",
      "args": ["-y", "tereno-mcp"]
    }
  }
}

Restart the client. Nothing else to configure — the free tools work immediately.

🆓 Free, no wallet needed

Tool	The question it answers
📖 tereno_catalog	What can Tereno answer, what does it cost, how long does each answer stay valid?
🏷️ tereno_price	What would this exact call cost right now — and does the answer already exist?
🧾 tereno_receipt	What did a settled call actually charge: tier, list price, credit applied, price paid?

tereno_price is the one worth knowing about. It names the reuse tier out loud:

hit      another agent already paid to compute this and it is still fresh
partial  the durable half survived; only the expired part is recomputed
miss     nothing to reuse — this call computes it, and the next asker pays less

💳 Paid per call

Tool	Price	The question it answers
🚦 transaction_intent_guard	$0.005	Is this safe to sign? Simulation, gas, balance and allowance deltas, unlimited-approval flags
🛡️ contract_guard	$0.001–3	Is this contract safe to interact with? (code, proxy, pause)
🕵️ contract_change	$0.001–2	Did it change since last look? (rug-pull-after-audit detector)
🪙 token_metadata	$0.001–3	What token is this, really? (name, symbol, decimals, supply)
🧬 contract_interface	$0.001–2	ERC-20? NFT? Proxy? One bounded probe
⛽ chain_snapshot	$0.001–2	Latest Base block, base fee and suggested gas, zero parameters
📄 web_compile	$0.001–5	Public URL → bounded Markdown with resolved links, citations and a reusable artifact
🔎 evidence_artifact	$0.001–3	Can this public artifact be reused? Provenance, field validity, recomputation input
🤝 demand_pledge	free	Name a capability you would pay for. Credit only after the same wallet pays for it later

Calling a paid tool returns a 402 carrying the payment challenge in error.data.paymentRequired, the payable resource URL in error.data.resource, and the terms (network, asset, amount, payTo) in error.data.offer.

Over stdio you cannot pay by retrying the tool call. stdio has no headers in either direction, so there is nowhere for a PAYMENT-SIGNATURE to travel back through. Two ways to settle, both of which leave this package never touching a private key:

• Pay the resource over HTTP. Sign error.data.paymentRequired with your x402 client and send the signed request to error.data.resource. It returns the same payload the tool would have, receipt included, billed once.
• Use the remote server instead of this package. If your client supports remote MCP, point it at https://www.tereno.xyz/api/mcp. That transport does have headers, so signing the challenge and retrying the same tool call is the normal flow and everything stays inside MCP.

🔒 transaction_intent_guard is never cached, shared or resold. An unsigned transaction is intent, and it stays with the wallet that paid for it.

⚙️ Configuration

Env	Default	Purpose
TERENO_WALLET	—	Base address announced before payment, so a challenge can be bound to the wallet that will settle it. Optional.
TERENO_BASE_URL	https://www.tereno.xyz	Point at another Tereno deployment.
TERENO_TIMEOUT_MS	45000	Upstream request timeout.
TERENO_EVIDENCE_INSTALLATION_ID	—	Optional stable random id for this MCP installation. It is hashed only when resolving evidence received from another agent; never use a wallet or secret.

🔐 What this package does and does not do

It is a stdio transport in front of the hosted endpoint at /api/mcp. Messages are forwarded verbatim, so the tool list, the prices and the payment challenge all come from the same place an HTTP agent sees — and this package needs no release when a capability changes.

The one thing it translates is payment, and the translation is lossy in one direction. Over HTTP the challenge arrives in a response header and the caller retries with a PAYMENT-SIGNATURE header. stdio has neither, so the challenge is folded into the JSON-RPC error payload where a client can still reach it, while the signature has no way back in. That is why a paid call is settled against the resource URL rather than by retrying the tool, and why a client that speaks remote MCP should prefer the hosted endpoint.

No private key is ever read, stored or transmitted. There are no dependencies, and the whole thing is one readable file — read it before you let it run on your machine.

If your client supports remote MCP servers, skip this package and point it straight at https://www.tereno.xyz/api/mcp.

🌱 How it stays cheap — the cooperative layer

Tereno is a shared-cache coordination layer, not just an API. The first agent to pay for a given piece of verified work seeds it for the whole network; every later agent that reuses that answer pays less, and the seeder earns a small, non-transferable credit that discounts its own future calls.

Safety is a public good with a private cost. By making the first computation earn from every reuse, the network turns "I paid to check this contract" into "I lowered the price of checking it for everyone, and my own checks got cheaper."

The honest fine print: rewards are non-transferable credits, capped per artifact. They fund your agent's budget, they are not yield.

Discovery, scoring, reputation, pricing and the global cache live in the closed Tereno backend. This server and its SDK (tereno-client) are the public, open interface to it.

🤝 Support & community

• 💬 Questions / setup → Tereno Discord
• 🐛 Bugs → issues · ⚠️ never paste private keys or .env
• 🔒 Vulnerabilities → report privately

🔗 Links

Live catalog · OpenAPI · MCP registry entry · plugin-tereno for ElizaOS · tereno-client SDK

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tereno.xyz · Verdicts before signatures, for agents on Base.