B20 Check
Verify B20 tokens on Base: issuer powers, imposter detection, signed EIP-712 verdicts.
Open source Open in the app JSON README (API)
About
Verify B20 tokens on Base: issuer powers, imposter detection, signed EIP-712 verdicts.
Details
- Kind
- MCP servers
- Topic
- No topic detected
- Publisher
- com.b20check
- Origin
- official
- Category
- ferramentas
- Transport
- http
- Version
- 0.1.1
- Added
- 2026-08-29 03:01:00
- Updated
- 2026-08-29 03:01:00
- Origin id
com.b20check/b20check
README
# b20check-mcp
An MCP (Model Context Protocol) server for [B20 Check](https://b20check.com). It lets Claude,
ChatGPT, or any MCP client verify a B20 token on Base before you touch it: you ask, in plain
language, whether a token is safe, and your assistant runs the check and reads you the signed
verdict.
## What it exposes
- `verify_b20_token(address)` — is this address a legitimate B20 token on Base, and what powers
does its issuer hold? Returns a verdict (ok / caution / danger), risk flags (mint, freeze,
seize, pause, admin, impostor, and more), data freshness (indexed / live / not_indexed), and an
EIP-712 signed attestation you can verify independently. A token that cannot be fully checked is
never signed as a clean pass.
- `b20_stats()` — how many B20 tokens B20 Check has indexed.
The tool description instructs the assistant to run the check before helping move value into a B20
token it has not already verified.
## Add to Claude Desktop
In `claude_desktop_config.json`:
```json
{
"mcpServers": {
"b20-check": {
"command": "npx",
"args": ["-y", "b20check-mcp"]
}
}
}
```
No-code alternative (no install): B20 Check also runs a remote MCP connector. Paste
`https://b20check.com/mcp` into Claude (Settings, Connectors) or add it in ChatGPT as a custom MCP
connector.
## Free vs paid
By default this server calls the free, rate-limited demo route (20 checks/minute, no wallet, no
keys). For unmetered access, set `B20_AGENT_KEY` to a Base private key that holds USDC; the server
then pays $0.01 per call via x402 through the paid `/v1/verify` endpoint.
| Env | Default | Meaning |
|-----|---------|---------|
| `B20_BASE_URL` | `https://b20check.com` | B20 Check API base URL |
| `B20_AGENT_KEY` | (unset) | 0x Base key holding USDC; enables paid, unmetered access via x402 |
Verify-don't-trust: the attestation is EIP-712 signed. Recover the signer
(`0x1388d1e3751512955A53C7c2795Eaf8a3B029e6A`) from the signature yourself rather than trusting the
`verdict` field alone.
MIT licensed.