Agent skill

Address Utils

by Nethereum in Nethereum/Nethereum

Validate and format Ethereum addresses with Nethereum. An agent skill from Nethereum/Nethereum.

MITAuto-check passedBackend & APIs

Install Address Utils

skills CLI
$ npx skills add Nethereum/Nethereum --skill address-utils -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install Nethereum/Nethereum address-utils --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/Nethereum/Nethereum.git skills-src && mkdir -p .claude/skills && cp -r skills-src/plugins/nethereum-skills/skills/address-utils .claude/skills/address-utils && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
address-utils
GitHub stars
2.3k
Token cost
~1.2k tokens
SKILL.md length
94 words
Files
1
Skills in repo
71
Repo updated
First seen
Licence
MIT

At a glance

Validate and format Ethereum addresses with Nethereum. An agent skill from Nethereum/Nethereum.

  • The user needs address validation
  • SKILL.md covers Required Usings, EIP-55 Checksum Addresses, Validate Address Format and Compare Addresses…, plus 4 more sections
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
  • EIP-55 checksum

What it does

Address Utils is an agent skill from Nethereum/Nethereum. Validate and format Ethereum addresses with Nethereum. Use when the user needs address validation, EIP-55 checksum, address comparison, zero address handling, UniqueAddressList, or address padding.

Its SKILL.md is about 1.2k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Backend & APIs. It works with Ethereum. The repository describes itself as: Ethereum .Net cross platform integration library. The licence is MIT.

When your agent uses it

  • The user needs address validation
  • EIP-55 checksum
  • Address comparison
  • Zero address handling

Example prompts

  • “/address-utils”

What it can do on your machine

Read from SKILL.md and the folder at commit 229f278. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md (its code samples are csharp).

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Address Utils loads about 1.2k tokens when it runs. Until then it costs about 53 tokens; SKILL.md has 94 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~53
When it runs · the whole SKILL.md, loaded when a task matches
~1.2k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from Nethereum/Nethereum at commit 229f278, republished under its MIT licence (© Nethereum). 94 words, ~1,234 tokens.

Download SKILL.mdSave it as .claude/skills/address-utils/SKILL.md (or your agent's skills folder).
name
address-utils
description
Validate and format Ethereum addresses with Nethereum. Use when the user needs address validation, EIP-55 checksum, address comparison, zero address handling, UniqueAddressList, or address padding.
user-invocable
true

Address Utilities with Nethereum

NuGet: Nethereum.Util

Source: UtilDocExampleTests

Required Usings

csharp
using System.Collections.Generic;
using Nethereum.Util;
using Nethereum.Hex.HexConvertors.Extensions;

EIP-55 Checksum Addresses

Mixed-case encoding that provides error detection without changing the address value.

csharp
var addressUtil = AddressUtil.Current;

var checksum = addressUtil.ConvertToChecksumAddress("0x5aaeb6053f3e94c9b9a09f33669435e7ef1beaed");
// "0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed"

// Works from all-uppercase too
var fromUpper = addressUtil.ConvertToChecksumAddress("0x5AAEB6053F3E94C9B9A09F33669435E7EF1BEAED");
// Same result: "0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed"

// Verify checksum
addressUtil.IsChecksumAddress("0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed"); // true
addressUtil.IsChecksumAddress("0x5aaeb6053f3e94c9b9a09f33669435e7ef1beaed"); // false

// Convert from raw bytes
var bytes = "5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed".HexToByteArray();
var checksumFromBytes = addressUtil.ConvertToChecksumAddress(bytes);

Validate Address Format

csharp
var addressUtil = AddressUtil.Current;

// Full validation (hex format, length, prefix)
addressUtil.IsValidEthereumAddressHexFormat("0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed"); // true
addressUtil.IsValidEthereumAddressHexFormat("not-an-address"); // false

// Length-only check (40 hex chars + 0x prefix)
addressUtil.IsValidAddressLength("0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed"); // true
addressUtil.IsValidAddressLength("0x1234"); // false

Compare Addresses (Case-Insensitive)

Ethereum addresses are case-insensitive for equality. Always use these methods instead of ==.

csharp
var addressUtil = AddressUtil.Current;

// Static method
addressUtil.AreAddressesTheSame(
    "0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed",
    "0x5AAEB6053F3E94C9B9A09F33669435E7EF1BEAED"); // true

// Extension method
"0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed"
    .IsTheSameAddress("0x5aaeb6053f3e94c9b9a09f33669435e7ef1beaed"); // true

Empty / Zero Address Handling

csharp
var addressUtil = AddressUtil.Current;

// Check for empty/null/zero
addressUtil.IsAnEmptyAddress(null);  // true
addressUtil.IsAnEmptyAddress("");    // true
addressUtil.IsAnEmptyAddress("0x0"); // true

// Extension methods
"0x0".IsAnEmptyAddress();           // true
"0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed".IsNotAnEmptyAddress(); // true

// Constants
AddressUtil.ZERO_ADDRESS;      // "0x0000000000000000000000000000000000000000"
AddressUtil.AddressEmptyAsHex; // Same zero address

// Safe accessor (returns zero address for null)
string nullAddr = null;
addressUtil.AddressValueOrEmpty(nullAddr);
// "0x0000000000000000000000000000000000000000"

UniqueAddressList and AddressEqualityComparer

Case-insensitive address collections that prevent duplicates regardless of casing.

csharp
// UniqueAddressList deduplicates automatically
var uniqueList = new UniqueAddressList();
uniqueList.Add("0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed");
uniqueList.Add("0x5AAEB6053F3E94C9B9A09F33669435E7EF1BEAED");
uniqueList.Add("0x5aaeb6053f3e94c9b9a09f33669435e7ef1beaed");
// uniqueList.Count == 1

// AddressEqualityComparer for Dictionary/HashSet
var comparer = new AddressEqualityComparer();
comparer.Equals(
    "0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed",
    "0x5AAEB6053F3E94C9B9A09F33669435E7EF1BEAED"); // true

// Use in Dictionary for case-insensitive key lookup
var dict = new Dictionary<string, int>(comparer);
dict["0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed"] = 100;
dict["0x5AAEB6053F3E94C9B9A09F33669435E7EF1BEAED"]; // 100

Pad Short Addresses (ConvertToValid20ByteAddress)

Left-pads a short hex value to a full 20-byte address. Useful when dealing with contract return values or CREATE2 results.

csharp
var addressUtil = AddressUtil.Current;

addressUtil.ConvertToValid20ByteAddress("0x1234");
// "0x0000000000000000000000000000000000001234"

addressUtil.ConvertToValid20ByteAddress(null);
// "0x0000000000000000000000000000000000000000"

Keccak-256 Hashing

Used internally for checksum calculation. Also available for general-purpose hashing.

csharp
var keccak = Sha3Keccack.Current;

// Hash a string
keccak.CalculateHash("hello");
// "1c8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8"

// Hash raw bytes
var bytes = new byte[] { 0x68, 0x65, 0x6c, 0x6c, 0x6f };
keccak.CalculateHash(bytes).ToHex();

// Hash from hex input
keccak.CalculateHashFromHex("0x68656c6c6f");

// Get result as byte array (32 bytes)
byte[] hashBytes = keccak.CalculateHashAsBytes("hello");

© Nethereum, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in plugins/nethereum-skills/skills/address-utils of Nethereum/Nethereum.

Open the folder on GitHubat commit 229f278

Compare with similar skills

Address Utils next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Address Utils compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Address Utils this skillNethereum/Nethereum2.3k—~1.2kAutomated safety check: PassMIT
NEAR Intents Swap Integrationinternet-court/internet-court-skill6.4k2 repos~939Automated safety check: PassCustom licence
Deposit QrSuperior-Trade/superior-skills2141 repos~1.1kAutomated safety check: PassMIT
Explorer Contract Verificationsablier-labs/evm-monorepo353—~1.9kAutomated safety check: PassCustom licence
Developing Smart ContractsLFDT-Lineth/lineth-monorepo126—~1.4kAutomated safety check: PassAGPL-3.0
Squash BugbotLFDT-Lineth/lineth-monorepo126—~3.3kAutomated safety check: PassApache-2.0

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Works with

Categories

Questions about Address Utils

What does Address Utils do?

Validate and format Ethereum addresses with Nethereum. An agent skill from Nethereum/Nethereum. Address Utils is an agent skill from Nethereum/Nethereum. Validate and format Ethereum addresses with Nethereum.

When should I use Address Utils?

Address Utils fits situations like: the user needs address validation; EIP-55 checksum; address comparison; zero address handling.

How do I install Address Utils in Claude Code?

Run `npx skills add Nethereum/Nethereum --skill address-utils -a claude-code`. Or copy the skill folder (plugins/nethereum-skills/skills/address-utils in Nethereum/Nethereum) into .claude/skills/address-utils in your project. Claude Code loads it when a task matches its description.

How do I install Address Utils in Codex?

Run `npx skills add Nethereum/Nethereum --skill address-utils -a codex`. Or copy the skill folder (plugins/nethereum-skills/skills/address-utils in Nethereum/Nethereum) into .agents/skills/address-utils in your project. Codex loads it when a task matches its description.

Can I use Address Utils in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add Nethereum/Nethereum --skill address-utils -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/address-utils, .gemini/skills/address-utils, .github/skills/address-utils and .opencode/skills/address-utils in your project.

What does Address Utils need to run?

SKILL.md names no scripts, command-line tools or credentials: Address Utils is instructions for the agent only.

Does Address Utils access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Address Utils safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Address Utils use?

Address Utils is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Address Utils use?

About 1.2k tokens (SKILL.md is roughly 4.9k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Address Utils?

Skills that share tags, products or a category with Address Utils: NEAR Intents Swap Integration (internet-court/internet-court-skill, 6.4k stars), Deposit Qr (Superior-Trade/superior-skills, 214 stars), Explorer Contract Verification (sablier-labs/evm-monorepo, 353 stars) and Developing Smart Contracts (LFDT-Lineth/lineth-monorepo, 126 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Address Utils?

Nethereum (a GitHub organization) maintains it in Nethereum/Nethereum, which has 2,260 GitHub stars. The repository holds 71 skills in this directory. The repository was last updated on October 5, 2026.

Source: Nethereum/Nethereum on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.