fallow
Codebase intelligence for TypeScript and JavaScript. Free static analysis of code and styles: unused code, duplication, circular deps, complexity hotspots, architecture boundaries, design-system drift. Optional paid runtime layer (Fallow Runtime): hot-path review and cold-path deletion evidence from
Fallow is a codebase intelligence agent skill for TypeScript and JavaScript projects that performs static analysis to detect unused code, circular dependencies, code duplication, complexity hotspots, architecture boundary violations, and design-system drift. It provides deterministic JSON output contracts designed for AI agent consumption, with exit codes 0 and 1 both indicating successful runs (1 signals findings exist). The skill includes an MCP server integration and ships with automated agent onboarding via npx fallow agent install for Claude Code, Codex, and Cursor.
Key Features
Use Cases
- 01AI agents auditing code changes before commit to prevent introducing unused exports or circular dependencies
- 02Agents performing safe refactoring with --symbol-impact to find exact consumers and affected tests before renaming
- 03Automated PR reviews identifying complexity hotspots and duplication in changed files only
- 04Onboarding agents using npx fallow recommend to detect project stack and propose configuration with rationale
- 05Code cleanup agents using fix --dry-run to preview removals, then applying auto-fixes after confirmation
- 06Security-focused agents reviewing reachability-ranked vulnerability candidates with fallow security
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fallow — FAQ
What is the fallow agent skill?+
Fallow is a codebase intelligence skill for TypeScript/JavaScript that AI agents use to analyze unused code, duplication, complexity, architecture boundaries, and styling drift. It outputs deterministic JSON contracts and ships with an MCP server plus built-in support for Claude Code, Codex, and Cursor.
How do I install the fallow agent skill?+
Run npm install --save-dev fallow to add it as a project dependency, then npx fallow agent install to automatically configure your agent harness (Claude Code, Codex, or Cursor) with the MCP server, skill files, and git hooks. Alternatively, manually add the MCP server config with npx fallow-mcp.
Which AI clients work with fallow?+
Fallow officially supports Claude Code, Codex, and Cursor via npx fallow agent install. The MCP server (fallow-mcp) works with any MCP-compatible client, including Claude Desktop.
Does fallow require API keys or external services?+
No API keys are needed for core static analysis. The free tier includes all detection features. The optional paid Fallow Runtime layer (for production execution evidence) requires a license obtained via npx fallow license activate --trial.
Is fallow free to use?+
Yes, all static analysis features are free under the MIT license. The optional Fallow Runtime layer for production coverage monitoring requires a paid license, but a single local coverage capture is free.
How do agents consume fallow output?+
Add --format json --quiet to any command for machine-readable JSON on stdout. Exit codes 0 and 1 both mean success (1 indicates findings), while exit 2 signals a real error with a JSON error envelope.
How do I install fallow?+
Open the source repository on GitHub and follow its README. fallow is a skill — MCP Agents Market links you directly to the official repo.
Is fallow free?+
fallow is an open-source project hosted on GitHub. Check the repository for its license and any usage requirements.