Add a rug-check to your LangChain agent

The @true402.dev/langchain package exposes true402's safety stalls as ready-made LangChain tools. Install it alongside @langchain/core:

1. Add the package: npm i @true402.dev/langchain @langchain/core
2. Set a PAYER_PRIVATE_KEY env var — a Base wallet the agent controls. In true402 the wallet is the identity: there is no account to create and no API key to manage.
3. Fund it later if you need volume — most safety stalls include a small free daily trial (deployer-check is the exception, see §04), so you can wire everything up and test before spending anything.

Under the hood each tool call is an x402 request: USDC on Base, pay-per-call, settled from the payer key you pass in.

One factory call returns an array of tools you can drop into any LangChain agent — createReactAgent, AgentExecutor, or your own graph. There is nothing else to register.

1. Import the factory: import { createTrue402Tools } from '@true402.dev/langchain';
2. Build the tools with your payer key: const tools = createTrue402Tools({ payerPrivateKey: process.env.PAYER_PRIVATE_KEY! });
3. Pass tools to your agent constructor exactly like any other LangChain tool array.

The agent can now call the stalls itself. The factory returns six tools: true402_token_report (POST /v1/base/token-report, composite avoid/caution/ok verdict, ~$0.01), true402_token_safety (POST /v1/token-safety, structural score 0-100, ~$0.005), true402_address_safety (POST /v1/base/address-safety, ~$0.005), true402_deployer_check (POST /v1/base/deployer-check, ~$0.008), true402_tx_preflight (POST /v1/base/tx-preflight, ~$0.008) and true402_liquidity_history (POST /v1/base/liquidity-history, ~$0.005). All hang off the API base https://true402.dev/api.

The last two cover what a pre-buy verdict cannot. true402_tx_preflight inspects the unsigned transaction the agent is about to sign — it takes no private key and no signature, so it cannot broadcast or front-run it — and returns a simulation against current state, the decoded intent (an unlimited approval is judged on the spender), and the counterparty's removal history. Call it last, immediately before signing. true402_liquidity_history reads what has already happened to the token's liquidity: every observed removal with amount, block and transaction hash, plus the other tokens drained in the same transaction. A live simulation is blind to this — a pool drained last month simulates fine today if it was re-seeded. Every answer states the block range the archive covers, so none observed is never a claim of safety.

Don't let the model decide in prose whether a token is safe. Make the rug-check a hard gate in your trade path: the agent must obtain a verdict from token-report and abort on anything that isn't ok.

1. Before any buy, call token-report with the token address.
2. Read the composite verdict: avoid → refuse the trade; caution → require an explicit override or downsize; ok → proceed.
3. For a cheaper first pass, gate on token-safety's 0-100 structural score, then escalate to token-report only for borderline tokens.

What makes the verdict trustworthy is that token-report runs a real on-chain buy/sell honeypot simulation via state-override eth_call — it actually proves the token can be sold, rather than pattern-matching source code. It also folds in liquidity, ownership/mint authority, and deployer reputation. A static scanner can be fooled by a token that looks clean but blocks sells; a simulated sell cannot.

There is no billing dashboard and no key to rotate. Payment is settled per call straight from the payer wallet:

1. Free daily trial — most safety stalls grant a small number of free calls per day, enough to build and test the gate without spending: token-report, token-safety, address-safety, tx-preflight and liquidity-history. deployer-check is excluded — it depends on a keyed third-party explorer API, so it is paid from the first call.
2. Per-call over x402 — beyond the trial, each call costs a few tenths of a cent in USDC on Base (~$0.005–$0.01 depending on the stall). The createTrue402Tools factory handles the 402 → pay → retry flow using PAYER_PRIVATE_KEY.
3. No account, no API key — the wallet is the identity, so onboarding a new agent is just funding a key.

See per-stall pricing and payloads in the API docs.

Before touching your agent code, sanity-check any Base token from the terminal — no install, no key, runs on the free trial:

1. Run npx @true402.dev/rugcheck 0x<token> against a token you already hold or are watching.
2. Or paste an address into the hosted checker at true402.dev/check to see the same verdict your agent will receive.

Once the output looks right, drop createTrue402Tools into your agent and make it the gate in front of every buy.