How do I install the Echidna skill?

Run npx skillmds@latest add hairyf/echidna in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

What does the Echidna skill do?

Property-based fuzzing and assertion testing for Ethereum smart contracts with Echidna. It is listed under Coding & Dev Tools on SkillMD.

Is Echidna safe to use?

This skill has not completed SkillMD's automated safety review yet. Capability flags: docs only. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Echidna?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Echidna free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Echidna?

hairyf (@hairyf) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Echidna by hairyf — Agent Skill

Name: Echidna
Rating: 4.2 (5 reviews)
Author: hairyf

File contents

Skill is based on Echidna (crytic/echidna), generated from source at the listed date.

Echidna is a property-based fuzzer for Ethereum smart contracts. It generates random sequences of contract calls to falsify invariants (Solidity functions named with a prefix like echidna_ that return bool) or to trigger Solidity assert failures. It supports coverage-guided fuzzing, corpus collection, multiple test modes, and integration with Foundry, Hardhat, and Truffle.

Core References

Topic	Description	Reference
Invariants	Defining and running property invariants (echidna_ prefix, no args, return bool)	core-invariants
Configuration	YAML config (testMode, gas, coverage, corpus, workers, filtering)	core-configuration
CLI	Invocation, contract selection, output drivers (text, json, none)	core-cli

Features

Topic	Description	Reference
Coverage and corpus	corpusDir, covered.txt, line markers, coverage reports	features-coverage
Build systems	Foundry, Hardhat, Truffle, echidna ., allContracts, solcLibs	features-build-systems
Test modes	property, assertion, overflow, exploration, optimization	features-test-modes
Function filtering	filterFunctions, filterBlacklist, whitelist/blacklist	features-filtering
Symbolic execution	symExec, SMT solver (cvc5, z3, bitwuzla), tuning options	features-symbolic
FFI and cheatcodes	allowFFI, HEVM cheatcode support	features-ffi-cheatcodes

Best practices

Topic	Description	Reference
Invariant patterns	Multi-sender, payable, gas/time, assertions vs invariants	best-practices-invariants

Advanced

Topic	Description	Reference
JSON output	Campaign/Test/Transaction schema for CI and scripting	advanced-json-output
Debugging	Profiling (+RTS -p -s), common performance causes	advanced-debugging

---name: echidnadescription: Property-based fuzzing and assertion testing for Ethereum smart contracts with Echidna.---> Skill is based on Echidna (crytic/echidna), generated from source at the listed date.Echidna is a property-based fuzzer for Ethereum smart contracts. It generates random sequences of contract calls to falsify invariants (Solidity functions named with a prefix like `echidna_` that return bool) or to trigger Solidity `assert` failures. It supports coverage-guided fuzzing, corpus collection, multiple test modes, and integration with Foundry, Hardhat, and Truffle.## Core References| Topic | Description | Reference ||-------|-------------|-----------|| Invariants | Defining and running property invariants (echidna_ prefix, no args, return bool) | [core-invariants](references/core-invariants.md) || Configuration | YAML config (testMode, gas, coverage, corpus, workers, filtering) | [core-configuration](references/core-configuration.md) || CLI | Invocation, contract selection, output drivers (text, json, none) | [core-cli](references/core-cli.md) |## Features| Topic | Description | Reference ||-------|-------------|-----------|| Coverage and corpus | corpusDir, covered.txt, line markers, coverage reports | [features-coverage](references/features-coverage.md) || Build systems | Foundry, Hardhat, Truffle, echidna ., allContracts, solcLibs | [features-build-systems](references/features-build-systems.md) || Test modes | property, assertion, overflow, exploration, optimization | [features-test-modes](references/features-test-modes.md) || Function filtering | filterFunctions, filterBlacklist, whitelist/blacklist | [features-filtering](references/features-filtering.md) || Symbolic execution | symExec, SMT solver (cvc5, z3, bitwuzla), tuning options | [features-symbolic](references/features-symbolic.md) || FFI and cheatcodes | allowFFI, HEVM cheatcode support | [features-ffi-cheatcodes](references/features-ffi-cheatcodes.md) |## Best practices| Topic | Description | Reference ||-------|-------------|-----------|| Invariant patterns | Multi-sender, payable, gas/time, assertions vs invariants | [best-practices-invariants](references/best-practices-invariants.md) |## Advanced| Topic | Description | Reference ||-------|-------------|-----------|| JSON output | Campaign/Test/Transaction schema for CI and scripting | [advanced-json-output](references/advanced-json-output.md) || Debugging | Profiling (+RTS -p -s), common performance causes | [advanced-debugging](references/advanced-debugging.md) |

Frequently asked questions

Echidna