Agent skill

Abi Retrieval

by Nethereum in Nethereum/Nethereum

Fetch contract ABIs from Sourcify, Etherscan, and 4Byte Directory using the composite ABIInfoStorage pattern (.NET/C).

MITAuto-check passedBackend & APIs

Install Abi Retrieval

skills CLI
$ npx skills add Nethereum/Nethereum --skill abi-retrieval -a claude-code

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

GitHub CLI
$ gh skill install Nethereum/Nethereum abi-retrieval --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/abi-retrieval .claude/skills/abi-retrieval && 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
abi-retrieval
GitHub stars
2.3k
Token cost
~1.5k tokens
SKILL.md length
149 words
Files
1
Skills in repo
71
Repo updated
First seen
Licence
MIT

At a glance

Fetch contract ABIs from Sourcify, Etherscan, and 4Byte Directory using the composite ABIInfoStorage pattern (.NET/C).

  • The user asks about ABI retrieval
  • SKILL.md covers Composite ABI Lookup…, Find Functions and Events, Sourcify V2 Direct and Etherscan API, plus 5 more sections
  • Calls dotnet
  • Contract verification

What it does

Abi Retrieval is an agent skill from Nethereum/Nethereum. Fetch contract ABIs from Sourcify, Etherscan, and 4Byte Directory using the composite ABIInfoStorage pattern (.NET/C). Use this skill when the user asks about ABI retrieval, contract verification, function signature lookup, calldata decoding, or Sourcify/Etherscan API usage.

Its SKILL.md is about 1.5k 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 C# and .NET. The repository describes itself as: Ethereum .Net cross platform integration library. The licence is MIT.

When your agent uses it

  • The user asks about ABI retrieval
  • Contract verification
  • Function signature lookup
  • Calldata decoding

Example prompts

  • “/abi-retrieval”

Requirements

  • A credential in YOUR_KEY

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

    Shell commands in SKILL.md call:

    • dotnet

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

  • Network

    Links to these hosts (documentation or services it may open):

    • nethereum.readthedocs.io

    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

Abi Retrieval loads about 1.5k tokens when it runs. Until then it costs about 73 tokens; SKILL.md has 149 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~73
When it runs · the whole SKILL.md, loaded when a task matches
~1.5k

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). 149 words, ~1,492 tokens.

Download SKILL.mdSave it as .claude/skills/abi-retrieval/SKILL.md (or your agent's skills folder).
name
abi-retrieval
description
Fetch contract ABIs from Sourcify, Etherscan, and 4Byte Directory using the composite ABIInfoStorage pattern (.NET/C#). Use this skill when the user asks about ABI retrieval, contract verification, function signature lookup, calldata decoding, or Sourcify/Etherscan API usage.
user-invocable
true

ABI Retrieval & Contract Verification

Nethereum.DataServices provides a composite ABI lookup system that chains multiple sources with automatic fallback: Sourcify → Etherscan → 4Byte Directory.

NuGet: Nethereum.DataServices

bash
dotnet add package Nethereum.DataServices

Use ABIInfoStorageFactory to create a fallback chain of ABI sources:

csharp
using Nethereum.DataServices.ABIInfoStorage;

// Full chain: cache → Sourcify → Etherscan → Sourcify4Byte → FourByte
var storage = ABIInfoStorageFactory.CreateDefault(etherscanApiKey: "YOUR_KEY");

// Get complete ABI
var abiInfo = await storage.GetABIInfoAsync(chainId: 1, contractAddress);
Console.WriteLine($"Contract: {abiInfo.ContractName}, Functions: {abiInfo.FunctionABIs.Count}");
Factory Presets
MethodSources
CreateDefault(etherscanApiKey, cache)Cache → Sourcify → Etherscan → Sourcify4Byte → FourByte
CreateWithSourcifyOnly(cache)Cache → Sourcify → Sourcify4Byte → FourByte
CreateWithEtherscanOnly(apiKey, cache)Cache → Etherscan → Sourcify4Byte → FourByte
CreateLocalOnly(cache)Cache only
CreateCustom(cache, storages...)Custom fallback chain
Custom Chain
csharp
var storage = ABIInfoStorageFactory.CreateCustom(
    cache: new ABIInfoInMemoryStorage(),
    new SourcifyABIInfoStorage(),
    new EtherscanABIInfoStorage("YOUR_KEY"),
    new FourByteDirectoryABIInfoStorage());

Find Functions and Events

csharp
// By 4-byte selector from input data
var func = await storage.FindFunctionABIFromInputDataAsync(chainId, contractAddress, inputData);

// By topic hash
var evt = await storage.FindEventABIAsync(chainId, contractAddress, topicHash);

// By error selector
var err = await storage.FindErrorABIAsync(chainId, contractAddress, errorSelector);
Batch Lookups
csharp
var functions = await storage.FindFunctionABIsBatchAsync(
    new[] { "0xa9059cbb", "0x095ea7b3", "0x23b872dd" });

var events = await storage.FindEventABIsBatchAsync(
    new[] { "0xddf252ad...", "0x8c5be1e5..." });

var combined = await storage.FindABIsBatchAsync(functionSignatures, eventSignatures);

Sourcify V2 Direct

csharp
using Nethereum.DataServices.Sourcify;

var sourcify = new SourcifyApiServiceV2();

// Get contract (ABI, sources, compilation, proxy resolution)
var contract = await sourcify.GetContractAsync(chainId: 1, contractAddress);

// Just ABI
string abi = await sourcify.GetContractAbiAsync(chainId: 1, contractAddress);

// Verify from Etherscan
var result = await sourcify.VerifyFromEtherscanAsync(chainId, address, etherscanApiKey);

// Verify with source files
var verifyResult = await sourcify.PostVerifyAsync(chainId, address, sourceFiles);
Proxy Resolution

SourcifyABIInfoStorage automatically resolves proxy contracts:

csharp
var sourcifyStorage = new SourcifyABIInfoStorage(); // resolveProxies: true
var abiInfo = await sourcifyStorage.GetABIInfoAsync(chainId, proxyAddress);
// Returns implementation ABI

Etherscan API

csharp
using Nethereum.DataServices.Etherscan;

var etherscan = new EtherscanApiService(chain: 1, apiKey: "YOUR_KEY");

var abiResponse = await etherscan.Contracts.GetAbiAsync(contractAddress);
var sourceResponse = await etherscan.Contracts.GetSourceCodeAsync(contractAddress);

4Byte Signature Lookup

FourByteDirectoryService
csharp
using Nethereum.DataServices.FourByteDirectory;

var fourByte = new FourByteDirectoryService();
var result = await fourByte.GetFunctionSignatureByHexSignatureAsync("0xa9059cbb");
// result.Results[0].TextSignature → "transfer(address,uint256)"
Sourcify4ByteSignatureService
csharp
using Nethereum.DataServices.Sourcify;

var sig4byte = new Sourcify4ByteSignatureService();

// Batch lookup
var result = await sig4byte.LookupAsync(
    functionSignatures: new[] { "0xa9059cbb", "0x095ea7b3" },
    eventSignatures: new[] { "0xddf252ad..." });

EVM Trace Decoding

csharp
using Nethereum.DataServices.ABIInfoStorage;

var decoded = program.DecodeWithSourcify(callInput, chainId: 1);
var decoded2 = program.Decode(callInput, chainId, etherscanApiKey: "YOUR_KEY");
var decoded3 = programResult.DecodeWithStorage(trace, callInput, chainId, storage);

Local Sourcify Database

For local storage of Sourcify data, use Nethereum.Sourcify.Database (EF Core + PostgreSQL):

csharp
using Nethereum.Sourcify.Database;

services.AddDbContext<SourcifyDbContext>(options => options.UseNpgsql(connectionString));
services.AddScoped<ISourcifyRepository, EFCoreSourcifyRepository>();

// Query
var sig = await repo.GetSignatureByHash4Async(selectorBytes);
var verified = await repo.GetVerifiedContractAsync(chainId, addressBytes);

Key Namespaces

NamespacePurpose
Nethereum.DataServices.ABIInfoStorageComposite ABI lookup factory and implementations
Nethereum.DataServices.SourcifySourcify V1/V2 API, Parquet exports, 4byte signatures
Nethereum.DataServices.EtherscanEtherscan V2 unified API
Nethereum.DataServices.FourByteDirectory4byte.directory API
Nethereum.DataServices.ChainlistChainlist RPC discovery

Documentation

© 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/abi-retrieval of Nethereum/Nethereum.

Open the folder on GitHubat commit 229f278

Compare with similar skills

Abi Retrieval 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.

Abi Retrieval compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Abi Retrieval this skillNethereum/Nethereum2.3k—~1.5kAutomated safety check: PassMIT
Tsp Csharpquerylenshq/ef-querylens225—~1.3kAutomated safety check: PassMIT
XML DocumentationVonage/vonage-dotnet-sdk118—~2.7kAutomated safety check: PassApache-2.0
Dotnet 10 Csharp 14sketch7/FluentlyHttpClient121—~2.2kAutomated safety check: PassMIT
DisCatSharp Discord DevelopmentAiko-IT-Systems/DisCatSharp140—~1.2kAutomated safety check: PassMIT
Foundationdb Advanced LayersSnowBankSDK/foundationdb-dotnet-client158—~3.4kAutomated safety check: PassBSD-3-Clause

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Works with

Categories

Questions about Abi Retrieval

What does Abi Retrieval do?

Fetch contract ABIs from Sourcify, Etherscan, and 4Byte Directory using the composite ABIInfoStorage pattern (.NET/C). Abi Retrieval is an agent skill from Nethereum/Nethereum.NET/C).

When should I use Abi Retrieval?

Abi Retrieval fits situations like: the user asks about ABI retrieval; contract verification; function signature lookup; calldata decoding.

How do I install Abi Retrieval in Claude Code?

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

How do I install Abi Retrieval in Codex?

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

Can I use Abi Retrieval 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 abi-retrieval -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/abi-retrieval, .gemini/skills/abi-retrieval, .github/skills/abi-retrieval and .opencode/skills/abi-retrieval in your project.

What does Abi Retrieval need to run?

Going by SKILL.md and its folder, Abi Retrieval needs the command-line tools its instructions call (dotnet). Our summary lists: A credential in YOUR_KEY.

Does Abi Retrieval access the network?

SKILL.md names 1 domain. As links in the text: nethereum.readthedocs.io. This is read from the text; nothing was executed.

Is Abi Retrieval 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 Abi Retrieval use?

Abi Retrieval 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 Abi Retrieval use?

About 1.5k tokens (SKILL.md is roughly 6k 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 Abi Retrieval?

Skills that share tags, products or a category with Abi Retrieval: Tsp Csharp (querylenshq/ef-querylens, 225 stars), XML Documentation (Vonage/vonage-dotnet-sdk, 118 stars), Dotnet 10 Csharp 14 (sketch7/FluentlyHttpClient, 121 stars) and DisCatSharp Discord Development (Aiko-IT-Systems/DisCatSharp, 140 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Abi Retrieval?

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.