What is onchain-decode?

A decoder for EVM blockchain data. EVM means the Ethereum Virtual Machine, the software system used by Ethereum and many compatible blockchains; the tool turns transaction bytes and event logs into readable JSON.

Use it to decode event logs and transaction calldata, look up function selectors, and retrieve ABI definitions. An ABI describes how a blockchain contract's functions and events are encoded.

Raw blockchain bytes are difficult to interpret without technical definitions. It helps explain what a transaction or event contains and identify function selectors.

onchain-decode — MCP server for Claude Code and Codex by zvmzaretsky: A decoder for EVM blockchain data.

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods

npx agentmods add mcp/zvmzaretsky/onchain-decode-mcp/onchain-decode

Clone the repo

git clone --depth 1 https://github.com/zvmzaretsky/onchain-decode-mcp

Made for: Claude Code, Codex, Cursor.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/mcp/zvmzaretsky/onchain-decode-mcp/onchain-decode.svg)](https://agentmods.dev/mcp/zvmzaretsky/onchain-decode-mcp/onchain-decode)

Your own site

<a href="https://agentmods.dev/mcp/zvmzaretsky/onchain-decode-mcp/onchain-decode"><img src="https://agentmods.dev/badge/mcp/zvmzaretsky/onchain-decode-mcp/onchain-decode.svg" alt="Measured on agentmods" height="20"></a>

Per session not measured What this adds to a session before it is invoked.

When invoked not measured Not applicable: nothing here is loaded into a session.

Security scan A 0 findings. Scan, not verified.

Origin original No closer match found in the catalogue.

Security

Grade A, and why

onchain-decode scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 5d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

server.json · 6 lines

What it actually says

{
  "onchain-decode": {
    "url": "https://decode.fabtally.com/mcp",
    "type": "streamable-http"
  }
}

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

5d ago First seen · 6 lines scan A 02c46b89667a

Subscribe to this mod's changes

onchain-decode is an MCP server published in the GitHub repository zvmzaretsky/onchain-decode-mcp (0 stars, last pushed 1mo ago), licensed MIT. Its token cost is not measured: an MCP server costs its tool schemas, not its config file. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Web3 and blockchain

onchain-decode

Getting it into your agent

Wrote this? Show the measurements

Grade A, and why

Nothing flagged

What it actually says

What this file has done since we first saw it

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