@eslint/mcp

Exposes ESLint's core linting engine as an MCP resource/tool, allowing Claude and other MCP clients to invoke ESLint rules against code without spawning separate processes. Implements ESLint's plugin architecture through MCP's tool-calling interface, enabling dynamic rule configuration and multi-file linting workflows within a single MCP session.

Automatically discovers and loads ESLint configuration files (.eslintrc.js, .eslintrc.json, .eslintrc.yml, eslintrc.config.js) from the project hierarchy, parses them, and applies rule sets and parser options to linting operations. Supports ESLint's cascading configuration model where nested .eslintrc files override parent configs, and handles environment-specific overrides (browser, node, es6, etc.).

Accepts a list of file paths or glob patterns and lints them in parallel using Node.js worker threads or async I/O, returning aggregated results with per-file diagnostics. Implements ESLint's caching layer to avoid re-linting unchanged files, and supports filtering results by severity (error, warning) or rule name.

Invokes ESLint's built-in --fix mechanism to automatically correct violations that have fix implementations (e.g., semicolon insertion, whitespace normalization). For violations without automatic fixes, generates structured suggestions with before/after code snippets and rule documentation links, enabling Claude to propose manual fixes or ask for user confirmation.

Exposes metadata for all loaded ESLint rules (name, description, category, fixable, deprecated status) and provides links to official documentation. Allows filtering rules by category (best-practices, errors, style, etc.) and searching by name or keyword, enabling Claude to explain rules to users and recommend relevant rules for specific code patterns.

Dynamically loads ESLint plugins (e.g., eslint-plugin-react, eslint-plugin-vue) from node_modules and registers their rules with the linting engine. Supports plugin configuration options and namespace-prefixed rules (e.g., react/jsx-uses-react). Validates plugin compatibility with the current ESLint version before loading.

Supports multiple ESLint parsers (default Espree, @babel/eslint-parser, @typescript-eslint/parser, vue-eslint-parser, etc.) and automatically selects the appropriate parser based on file extension and ESLint configuration. Handles parser options (ecmaVersion, sourceType, parserOptions) and validates parser compatibility with the target file type.

Filters linting results by severity level (error, warning, off) and aggregates statistics across multiple files. Supports custom severity mappings (e.g., treat warnings as errors) and generates summary reports with violation counts, most-violated rules, and files with the most issues. Enables Claude to provide targeted feedback based on severity thresholds.