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MCP Bytesmith

by laszlopere

Local MCP tools for encoding, hashing, conversions, random generation, and optional Ethereum and serialization workflows.

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Install MCP Bytesmith

Pick your client, then add it in one click or paste the config.

STDIOPython
~/Library/Application Support/Claude/claude_desktop_config.json
claude_desktop_config.json
{
  "mcpServers": {
    "laszlopere-mcp-bytesmith": {
      "command": "uvx",
      "args": [
        "mcp-bytesmith"
      ]
    }
  }
}

Settings → Developer → Edit Config, merge this into mcpServers, then fully quit and reopen Claude Desktop.

Install not yet sandbox-tested— we haven't run this command through our automated sandbox yet. Not a red flag; we're working through the catalog.

Overview

laszlopere/mcp-bytesmith MCP server provides local byte, text, hashing, number, identifier, and cryptography utilities through the Model Context Protocol. Its core tools use Python’s standard library, while Ethereum/EVM and serialization capabilities are enabled with optional extras. Operations run locally without network calls or remote APIs. Reach for it when an agent needs deterministic data transformations, checksums, key-related utilities, or EVM encoding and decoding.

Use cases

  • Convert payloads between hex, Base64, Base32, Base58, and Base45
  • Verify local file checksums and compare expected digests
  • Generate tokens, passphrases, UUIDs, ULIDs, and nanoids
  • Encode, decode, and inspect Ethereum ABI, calldata, logs, and revert data
  • Serialize or decode structured data with optional format toolsets

Key features

  • Local encoding, decoding, hashing, HMAC, and CRC operations
  • Base conversion and byte-sequence editing
  • CSPRNG tokens, passphrases, identifiers, and key derivation
  • Optional Ethereum and EVM primitives
  • Optional CBOR, MessagePack, bencode, ASN.1, SSZ, and protobuf decoding

Security & health

What it can reach and how reliably it runs — from our own checks, not the maintainer’s claims.

ActiveLast checked 1d ago

Recent health check succeeded.

21/21 checks healthy over the last 86d

Supply-chain signal

No high-severity advisories surfaced by our automated scan.

Critical 0High 0Medium 0Low 0

Scanned 10h ago via OSV.dev · mcp-bytesmith (PyPI)

Adoption & maintenance

Factual signals from GitHub, npm, and our automated checks — not a rating.

GitHub stars2Stargazers on the source repository.
Last commit22d agoMost recent push to the default branch.
Directory activity3 viewsConfig copies, upvotes, and views on AllMCPs.

How MCP Bytesmith works

What laszlopere/mcp-bytesmith MCP server does

laszlopere/mcp-bytesmith MCP server exposes a broad collection of local data and cryptography primitives through FastMCP, the official Python MCP SDK. The core package handles byte encoding and decoding, hashing, keyed authentication, integer base conversion, byte manipulation, URI processing, text normalization, character-set conversion, string escaping, Unicode inspection, random value generation, identifier creation, password hashing, and key derivation.

The core tools are built on the Python standard library and do not require network access. An info tool reports active toolsets and version information. This makes the server suitable for agents that need to inspect or transform supplied data without sending it to a remote service.

How it works

The server communicates over MCP and can be started locally over stdio. Tool calls perform calculations in the local Python process. The encode and decode tools cover formats such as hexadecimal, Base64 variants, Base32 variants, Base58 and Base58check, and Base45. Hashing includes cryptographic, CRC, and fast non-cryptographic digests; hash_file reads a local file and can compare its digest with an expected value.

Optional toolsets add domain-specific functions. The Ethereum extra covers Keccak-256, EIP-191 and EIP-712 hashing, ABI and RLP codecs, selectors, calldata, event logs, revert data, bytecode, transactions, storage slots, checksummed addresses, ENS hashes, mnemonic and HD derivation, and contract addresses. The serialization extra adds CBOR, MessagePack, bencode, ASN.1 DER/BER, SSZ, and raw protobuf-wire decoding. Some of these capabilities require the relevant optional dependencies.

Setup and configuration

Install and run the distribution with uvx mcp-bytesmith, or use a development checkout with uv sync followed by uv run mcp-bytesmith. The package requires Python 3.10 or newer. Core functionality is available without extra dependencies.

Install the ethereum extra to activate the Ethereum/EVM tools. Install the serialize extra for the serialization toolset. The README also refers to a crypto extra for bcrypt, Argon2 variants, and ASN.1 support. No environment variables or remote service credentials are documented as required.

Tools and capabilities

Core capabilities include:

  • Encode and decode common binary and textual representations.
  • Calculate hashes, CRC values, HMACs, and file checksums.
  • Convert integers between bases and edit byte sequences by padding, trimming, slicing, or concatenating.
  • Build and parse data: and otpauth:// URIs.
  • Normalize Unicode, transcode character sets, escape strings, and inspect code points.
  • Generate CSPRNG-backed bytes, tokens, passphrases, UUIDs, ULIDs, and nanoids.
  • Create and verify password storage strings, or derive raw key material with PBKDF2, scrypt, or HKDF.

With the optional Ethereum toolset, laszlopere/mcp-bytesmith MCP server can encode and decode ABI and RLP data, inspect contract ABIs, calculate selectors, decode logs and revert payloads, disassemble deployed bytecode, calculate storage slots, and derive several Ethereum-related values. The serialization toolset uses a format selector and, where needed, an explicit schema.

Limitations and notes

The server performs local computations and makes no network calls, so it does not query blockchains, resolve names online, or retrieve external files. File hashing operates on files available to the local process. Protobuf support is decode-only and, without a .proto schema, reports wire-level information rather than field names. SSZ encoding and decoding depend on a supplied schema. The project notes that additional cryptography, identifier, and validation toolsets remain on the roadmap.

The project is licensed under GPLv3. The bundled EFF passphrase list and BIP-39 English wordlist have separate licenses described in the repository.

Read the full README View source on GitHub

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Frequently Asked Questions about MCP Bytesmith

laszlopere/mcp-bytesmith is an MCP server that connects AI agents to local byte and cryptography utilities, including encoding, decoding, hashing, HMAC, random generation, base conversion, and key derivation. Optional extras add Ethereum/EVM codecs and hashing plus serialization formats. It runs computations locally without network calls.

Install it with `uvx mcp-bytesmith`, or use a checkout with `uv sync` and `uv run mcp-bytesmith`. Python 3.10 or newer is required. Install the `ethereum` or `serialize` extras when those optional toolsets are needed.

Yes, it is designed for local computation and makes no network calls or remote API requests. File-related operations use files available to the local process, while encoding, hashing, conversion, and other transformations run locally.

Yes, the optional Ethereum toolset includes tools for splitting calldata into named arguments and decoding receipt logs into named event arguments. It also includes ABI inspection, revert-data decoding, selectors, ABI/RLP codecs, and related Ethereum primitives.

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