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FabTally Decode

by zvmzaretsky · remote · no sign-in to list tools · v1.0.0 · published by GitHub user zvmzaretsky

Decode EVM bytes to JSON: event-log decoder, calldata explainer, selector lookup, ABI fetch.

Final · 1
CompareRegistry entry

4 tools: 1 do something that can't be undone and 3 only read.

Scanned Oct 21, 2026

No check matched anything in the tool definitions. No finding is not a safety guarantee. How the checks work.

claude mcp add --transport http onchain-decode https://decode.fabtally.com/mcp

Tools

Open a tool for its reasons and full description. Descriptions are the publisher's own words, shown as they are.

4 tools

Can't be undone 1Claude Code: ask
  • decode_calldataPAID $0.002 (x402, USDC on Base).No findings

    Why it is in this group

    • The input addresses people (input.to): what it sends cannot be taken back.
    Description, as the server wrote it
    PAID $0.002 (x402, USDC on Base). Decode a contract function call. Give {chain, to?, data, abi?}; get the 4-byte selector resolved to a function signature (via provided ABI, the verified contract source, or 4byte.directory) plus fully decoded, typed arguments (tuples/arrays/nested included). Without payment returns the x402 challenge.
Only reads 3Claude Code: allow
  • abi_fetchPAID $0.002 (x402, USDC on Base).No findings

    Why it is in this group

    • The name "abi_fetch" says "fetch": a word for reading.
    Description, as the server wrote it
    PAID $0.002 (x402, USDC on Base). Fetch the verified ABI + metadata for a contract. Give {address, chain}; get the ABI JSON, verification status/source (Sourcify or Blockscout), the callable function/event signatures, and full proxy-implementation resolution (EIP-1967/1822/OZ-legacy/beacon) — returning the implementation's ABI when it's a proxy. Without payment returns the x402 challenge; pass x_payment to settle.
  • decode_logPAID $0.003 (x402, USDC on Base).No findings

    Why it is in this group

    • The name "decode_log" says "log": a word for reading.
    Description, as the server wrote it
    PAID $0.003 (x402, USDC on Base). FLAGSHIP: decode EVM event LOGS to human-readable JSON. Give {chain, tx_hash} to decode every log in a transaction, OR {chain, address, topics[], data} for a single log; optional {abi}. Returns each event's name, canonical signature and named/typed args — correctly handling tuple/array/nested params, anonymous events, and indexed vs non-indexed. Resolves the ABI via Sourcify/Blockscout + 4byte event signatures when none is supplied. Without payment returns the x402 challenge; pass x_payment to settle.
  • selector_lookupPAID $0.001 (x402, USDC on Base).No findings

    Why it is in this group

    • The name "selector_lookup" says "lookup": a word for reading.
    Description, as the server wrote it
    PAID $0.001 (x402, USDC on Base). Resolve a 4-byte function selector (0x + 8 hex) OR a 32-byte event topic hash (0x + 64 hex) to its human-readable signature(s) via 4byte.directory + openchain.xyz. Returns all matches (selectors can collide) with a verified flag. Without payment returns the x402 challenge; pass x_payment to settle.

This is not a safety rating, and no finding is not a safety guarantee. The groups and findings come from fixed checks of the tool definitions the server returned on the date shown, not from its code or what it does when called. How the checks work.

Install

Pinned to version 1.0.0. Values in angle brackets are yours to fill in.

claude mcp add --transport http onchain-decode https://decode.fabtally.com/mcp

Run in a terminal.

Claude Code permissions

Allow the reads, ask before a change, deny the deletes. Paste into .claude/settings.json.

.claude/settings.json
{
  "permissions": {
    "allow": [
      "mcp__onchain-decode__decode_log",
      "mcp__onchain-decode__selector_lookup",
      "mcp__onchain-decode__abi_fetch"
    ],
    "ask": [
      "mcp__onchain-decode__decode_calldata"
    ],
    "deny": []
  }
}

Tools that only read are allowed, tools that change things ask first, tools that delete or cancel are denied. It assumes the server is installed as onchain-decode. Review it before you use it.