Reverse Engineer

reverse-engineer server

The read-only MCP server and CLI behind the reverse-engineer skill. The skill is the agent-facing entry point; this server replaces the commands that are missing or fragile on a given platform (otool, strings, jq, go version -m, asar extraction) with TypeScript parsers, and answers in at most 8 KB with citable locations. Installing the skill does not install the server.

Tools

The catalog is about 6 KB for the 8 tools; the skill is about 5.5 KB.

Design rules:

• Compact by default. Each answer stays under REVERSE_ENGINEER_MAX_BYTES (8192). Longer output is written to the cache, and the answer ends with its path, so read and search can page through it.
• Cited facts. Every location is file:line:col, file@0xoffset, a symbol or a string.
• No blocking on common cases. A .node file signed after packaging shows up as an unverified hash, not as an error. Malformed or hostile binaries degrade to partial results instead of hanging.
• Read-only. The tools never run the target. They write only to their cache: %LOCALAPPDATA%\reverse-engineer\cache, ~/Library/Caches/reverse-engineer, or $XDG_CACHE_HOME/reverse-engineer (override with REVERSE_ENGINEER_CACHE). Exceptions: Ghidra refuses project paths with a dot folder, so with such a cache path (the Linux default ~/.cache) its projects go to a private per-user folder in the temp directory; when the cache path contains a space, Ghidra keeps its settings in the home folder; jadx and the .NET SDK may write their own settings there on first use.
• Cache by SHA-256. An extraction or an analysis is reused.

Use

Requirements: Node.js 24.11 or later. Optional: Ghidra 11+ with JDK 21 for decompile, ilspycmd (.NET 10 SDK) and jadx (JDK 21) for managed. The agent can install them with the skill's install guide: official releases go into a per-user tools root (%LOCALAPPDATA%\reverse-engineer\tools, ~/Library/Application Support/reverse-engineer/tools, or $XDG_DATA_HOME/reverse-engineer/tools; override with REVERSE_ENGINEER_TOOLS), without admin rights or a PATH change. The tools look there first, then on PATH, GHIDRA_INSTALL_DIR and the usual install folders.

The package is published to npm as an alpha prerelease, reverse-engineer, and listed in the MCP Registry as io.github.Firzus/reverse-engineer. Pin the exact version:

npx -y reverse-engineer@0.1.0-alpha.2 triage ./some.exe

npx -y reverse-engineer@0.1.0-alpha.2 electron_surface "C:\Program Files\App" --focus audio,microphone

Claude Code MCP configuration (project .mcp.json):

{

"mcpServers": { "reverse-engineer": { "command": "npx", "args": ["-y", "reverse-engineer@0.1.0-alpha.2", "mcp"] } } }

On Windows, use "command": "cmd" with "args": ["/c", "npx", "-y", "reverse-engineer@0.1.0-alpha.2", "mcp"]. To run an unreleased build from a clone, run the Develop commands, then point the configuration at node /mcp/reverse-engineer/dist/cli.mjs mcp.

Install the skill with npx skills add Firzus/agent-skills --skill reverse-engineer.

Develop

The toolchain is Vite+ (vite-plus, local dev dependency). .github/workflows/reverse-engineer-check.yml runs the same checks on Windows, macOS and Linux:

npm install

npx vp check # format, lint, type check npx vp test # unit tests on synthetic and hostile fixtures npx vp pack # bundle dist/cli.mjs, a single file with no runtime dependency

Tests against real targets are opt-in: set RE_TARGETS (a folder with app.asar, app.asar.unpacked/ and gh.exe), RE_NOTION_DIR (an installed Notion app), RE_GHIDRA=1, RE_DOTNET_DLL, or RE_APK.

Release

.github/workflows/reverse-engineer-publish.yml publishes to npm and the MCP Registry. Merging a version change to main publishes it, so treat the merge as the release decision. In the release pull request:

1. Set the same version in package.json, package-lock.json, server.json, the pinned commands above and in the skill's SKILL.md; a unit test checks the first three. When vp pack reports a new bundled dependency, add its license to THIRD_PARTY_NOTICES.md.
2. Run the Develop checks, then npm pack (it rebuilds dist/) and inspect the tarball: LICENSE, README.md, THIRD_PARTY_NOTICES.md, dist/cli.mjs, ghidra/ExportDecompiled.java, package.json.

The workflow stops when the version is already on npm and the MCP Registry. Otherwise it runs the check workflow, builds the tarball in a job without publishing rights, then publishes in the release environment, from a job that runs no project or dependency code. npm uses trusted publishing, with a prerelease published under its own dist-tag (alpha), never latest; the MCP Registry uses its GitHub OIDC login. A last job runs the published --version. When a run fails, fix the cause and use Re-run all jobs on that run: each publication step rechecks its registry and skips what already exists. Never overwrite or unpublish a version to hide a failed release; publish a new one.

npm must trust the workflow before the first automated release: in the reverse-engineer package settings, add a GitHub Actions trusted publisher with user Firzus, repository agent-skills, workflow reverse-engineer-publish.yml and environment release.

Benchmark

bench/ adapts the harness from leanrea to Windows and compares four arms: no skill, leanrea, REA (MCP and skill), and this tool. See bench/BENCHMARK.md for the method, the results and their limits.

License

MIT. The benchmark tasks and harness are adapted from leanrea, MIT-licensed; its notice is in bench/LICENSE-leanrea. Fuse names and the Go build-info layout follow the public formats documented by Electron and the Go toolchain; no code is copied from REA.