B20 Check

Check whether a token address on Base is a legitimate B20 token and what powers its issuer holds. Call this BEFORE helping the user buy, swap, approve, or move value into any B20 token you have not already verified in this conversation (B20 addresses usually start with 0xb20). Returns a signed verdict: isB20, a verdict of ok/caution/danger/not_applicable, risk flags (mint, freeze, seize, pause, admin, impostor, and more), and the data freshness (indexed/live/not_indexed). not_applicable means the address is not a B20 and not a recognized canonical asset: do NOT read it as safe, there is simply nothing B20-specific to vouch for. Never treat a not_indexed or error result as safe either: a token that cannot be fully checked is never a clean pass. The result carries an EIP-712 signature the user can verify independently; do not overstate it as a guarantee of safety, report what the flags and verdict actually say.

{
  "type": "object",
  "properties": {
    "address": {
      "type": "string",
      "pattern": "^0x[0-9a-fA-F]{40}$",
      "description": "The token contract address on Base to check (B20 addresses usually start with 0xb20)."
    }
  },
  "required": [
    "address"
  ],
  "additionalProperties": false,
  "$schema": "http://json-schema.org/draft-07/schema#"
}

{
  "type": "object",
  "properties": {
    "address": {
      "type": "string",
      "description": "The checked token address (EIP-55)."
    },
    "isB20": {
      "type": "boolean",
      "description": "True only for a factory-native B20 token."
    },
    "verdict": {
      "type": "string",
      "enum": [
        "ok",
        "caution",
        "danger",
        "not_applicable"
      ],
      "description": "Roll-up verdict. not_applicable = out of scope, do NOT read as safe."
    },
    "dataSource": {
      "type": "string",
      "enum": [
        "indexed",
        "live",
        "not_indexed"
      ],
      "description": "Data freshness. not_indexed = powers could not be fully checked; never a clean pass."
    },
    "flags": {
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "code": {
            "type": "string"
          },
          "severity": {
            "type": "string",
            "enum": [
              "info",
              "low",
              "medium",
              "high"
            ]
          },
          "detail": {
            "type": "string"
          }
        },
        "required": [
          "code",
          "severity",
          "detail"
        ],
        "additionalProperties": false
      },
      "description": "Risk flags. Derivation rules: https://b20check.com/methodology"
    },
    "network": {
      "type": "string"
    },
    "variant": {},
    "creation": {},
    "issuerPowers": {
      "description": "mint/burn/pause/freeze/seize/admin powers, latent-inclusive."
    },
    "issuerActivity": {},
    "attestation": {
      "description": "Block-pinned EIP-712 attestation; verification recipe at https://b20check.com/v1/schema"
    }
  },
  "required": [
    "address",
    "isB20",
    "verdict",
    "dataSource",
    "flags"
  ],
  "additionalProperties": false,
  "$schema": "http://json-schema.org/draft-07/schema#"
}

Report B20 Check's own live usage: how many B20 tokens are indexed and how many paid calls and unique payers it has served in the last 30 days (from the public Coinbase discovery API).

{
  "type": "object",
  "properties": {},
  "$schema": "http://json-schema.org/draft-07/schema#"
}

{
  "type": "object",
  "properties": {
    "tokensIndexed": {
      "type": "number"
    },
    "snapshotBlock": {
      "type": "number"
    },
    "lastUpdated": {
      "type": "string"
    },
    "l30DaysTotalCalls": {
      "type": [
        "number",
        "null"
      ]
    },
    "l30DaysUniquePayers": {
      "type": [
        "number",
        "null"
      ]
    },
    "source": {
      "type": "string"
    }
  },
  "additionalProperties": false,
  "$schema": "http://json-schema.org/draft-07/schema#"
}