# Base Token Safety Check

> Base Token Safety Check is a paid API for AI agents from base-token-check.fly.dev, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-18).

Checks a Base ERC-20 token contract address and returns allow, warn, or block based on supply concentration, proxy patterns, and dangerous bytecode selectors.

## Facts

- Endpoint: GET https://base-token-check.fly.dev/v1/token-check?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-18
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/base-token-safety-check-43889468
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_mzK7zSCAVjVRZJxj3HxFo

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability base-token-safety-check-43889468
```

Example prompt: Before you buy any of this token, check if contract address 0x1234567890abcdef1234567890abcdef12345678 on Base is safe — I want to know if it should be allowed, warned about, or blocked due to supply concentration, proxy patterns, or mint/pause functions.

## When to prefer this

Use this endpoint when an AI agent is about to buy, swap into, or hold an ERC-20 token on the Base network and needs a lightweight pre-flight safety check. It is purpose-built for agentic trading workflows that require a fast allow/warn/block signal rather than a full audit. Prefer this over manual inspection when automating token purchases at scale or when integrating a safety gate into a DeFi agent loop. It is not a substitute for a full smart contract audit but is ideal as a fast, cheap ($0.01 USDC) first-pass filter.

## Known failure modes

- Invalid address format (not a 0x-prefixed 40-hex-character string) causes request rejection
- Address is an EOA or non-contract — verdict is 'block' with reason not-a-contract
- Token has no detectable ERC-20 interface — verdict is 'block' with reason not-an-erc20
- Network or RPC unavailability may cause timeout or 5xx error
- Proxy contracts may obscure underlying logic — proxy warning issued but full audit not possible
- Mint/pause selector presence does not confirm public callability — may produce false-positive warns

## How this service works

Base ERC-20 check before an agent buys or holds a token. Input: one contract address. Output: allow, warn, or block. Block: not a contract, not an ERC-20, zero supply, or the owner or token contract holds at least 50 percent. Warn: 20 to 50 percent held, proxy (EIP-1967, EIP-1167, or implementation()), or bytecode contains mint or pause. A selector does not prove the public can call it. Concentration covers only the owner and the token contract. Not an audit.

## Output

Returns a verdict of 'allow', 'warn', or 'block'. Block conditions: the address is not a contract, not an ERC-20, has zero supply, or the owner or token contract itself holds ≥50% of supply. Warn conditions: 20–50% concentration, presence of proxy patterns (EIP-1967, EIP-1167, or implementation()), or bytecode containing mint or pause selectors. Allow means none of the above triggers fired. This is a heuristic screen, not a formal audit.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "address"
     ],
     "properties": {
      "address": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{40}$",
       "description": "ERC-20 contract address on Base to check for supply concentration, proxy, mint, and pause."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/base-token-safety-check-43889468/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from base-token-check.fly.dev](https://www.zero.xyz/host/base-token-check.fly.dev/llms.txt)