mcp-code-context

mcp-code-context

MCP server with Tree-sitter WASM parsers for 100% AST accuracy. Zero native dependencies.

🚀 Quick Start (Claude Desktop)

• Install: npm install -g mcp-code-context
• Configure: Add to claude_desktop_config.json:

{
  "mcpServers": {
    "code-context": {
      "command": "npx",
      "args": ["-y", "mcp-code-context"]
    }
  }
}

• Enjoy: Use symbols like @code-context to map repos or edit code surgically.

No build tools required - Works on Windows/Mac/Linux without Visual Studio, Python, or node-gyp.

Works with Claude Desktop, Cursor, Windsurf, GitHub Copilot, Amazon Q, and any Model Context Protocol compatible client.

The Problem

LLMs working with code face two bottlenecks:

• Reading: Sending raw source files wastes the context window on function bodies and boilerplate. A 500-line file might contain only 30 lines of structural information the LLM needs.
• Writing: Rewriting entire files to change one function is error-prone, token-expensive, and risks corrupting unrelated code.

The Solution

mcp-code-context provides 11 tools — 5 for reading, 1 for cleanup, and 5 for writing — that operate at the symbol level (functions, classes, methods). Furthermore, tools support a className scope which correctly isolates identical symbol names in the same file (e.g. Flutter build() methods) to avoid reading or changing the wrong logic. Read tools extract structural skeletons. Write tools splice changes into the exact AST location.

File	Original	Compressed	Reduction
PHP class (426 lines)	426	60	85.9%
Dart repository (230 lines)	230	30	87.0%
PHP config (68 lines)	68	15	77.9%

Reliability & Testing

Built to be robust and precise. Both read and write engines are tested against real-world, complex codebases (including nested generic types in Dart, complex interfaces in PHP, and multi-file rename operations) with a 100% test pass rate across all languages and operations.

Features

Read

• 🌳 AST-based compression — Real Tree-sitter WASM parsers for TypeScript/JavaScript/Python/PHP/Dart. Zero regex-based parsing.
• 🔬 Surgical symbol extraction — Extract a single function, class, or method from a file by name. Use className to scope disambiguation (e.g., getting multiple build() methods in Dart).
• 💥 Impact analysis — Discover all files that depend on a given file before refactoring. Supports ES imports, CommonJS require(), Python imports, PHP use/require_once/include, and Dart imports.
• 📁 Smart file walking — Respects .gitignore and .repomixignore rules. Automatically excludes node_modules, dist, vendor, .git, etc.
• 📄 Multi-format output — XML (optimized for LLM consumption) or Markdown (human-readable).

Write

• ✏️ Surgical symbol replacement — Replace a function, method, or class body without touching the rest of the file. Narrow down the target using the className parameter.
• ➕ Precise code insertion — Insert new code before/after a symbol, or inside a class at the start/end.
• 🔄 Repository-wide rename — Rename a symbol in its definition AND all files that import it, atomically.
• 🗑️ Safe symbol removal — Delete code with automatic dependency checking to prevent breakage.
• 🔍 Mandatory dry-run flow — Write tools return a preview diff and a confirmationToken by default. Changes are only applied after explicit confirmation.
• 💾 Robust rolling backups — Automatically keeps the last 5 versions of modified files in a hidden .mcp-backups/ directory.
• ⏪ Surgical rollback — Revert files to any of the 5 previous states using the new rollback_file tool.
• 🤖 Fuzzy symbol matching — When a symbol is not found, the server provides structured suggestions based on Levenshtein distance.
• 🔐 Private symbol support — Full support for _ and __ prefixed symbols in Dart and Python.

Supported Languages

Language	Read (Compress + Extract)	Write (Replace + Insert + Rename + Remove)	Import Analysis
TypeScript / JavaScript	✅ AST (Tree-sitter WASM)	✅ AST (Tree-sitter WASM)	✅
PHP	✅ AST (Tree-sitter WASM)	✅ AST + line-splice	✅
Dart	✅ AST (Tree-sitter WASM)	✅ AST + line-splice	✅
Python	✅ AST (Tree-sitter WASM)	✅ Indentation-aware	✅
Others (JSON, YAML, CSS, etc.)	Passthrough / truncation	—	—

⚠️ Known Limitations

rename_symbol Tool

Dart and Python: Cross-file rename is NOT supported for .dart, .py, and .pyi files.

• Reason: No AST parser available for safe cross-file refactoring
• Risk: Regex-based rename may corrupt strings, comments, or unrelated code
• Recommendation: Use IDE refactoring tools instead:
  • Dart: VS Code with Dart extension (F2 key) or IntelliJ IDEA
  • Python: PyCharm, VS Code with Pylance (F2 key)
• Alternative: Use write_file_surgical to rename within a single file

TypeScript, JavaScript, PHP: Fully supported with AST-aware renaming ✅

get_semantic_repo_map Tool

• Max files: Limited to 500 files to prevent timeouts
• Performance: Synchronous I/O may take 10-30 seconds on large repositories
• Recommendation: Use @folder syntax to target specific directories

General

• Validation: No automatic syntax checking after edits. Always review diffs carefully before confirming.
• Backups: 5-version rolling backup system. Use rollback_file if something goes wrong.
• Large files: Files >10MB are skipped for safety.

Installation

# Clone the repository
git clone https://github.com/YOUR_USERNAME/mcp-code-context.git
cd mcp-code-context

# Install dependencies (no build tools required!)
npm install

# Build
npm run build

Note: Unlike v2.x, this version uses web-tree-sitter (WASM) instead of native bindings. No Visual Studio, Python, or node-gyp required!

Configuration

Claude Desktop

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "mcp-code-context": {
      "command": "node",
      "args": ["/absolute/path/to/mcp-code-context/dist/index.js"]
    }
  }
}

Cursor

Add to your Cursor MCP settings (.cursor/mcp.json):

{
  "mcpServers": {
    "mcp-code-context": {
      "command": "node",
      "args": ["/absolute/path/to/mcp-code-context/dist/index.js"]
    }
  }
}

Windsurf

Add to your Windsurf MCP config:

{
  "mcpServers": {
    "mcp-code-context": {
      "command": "node",
      "args": ["/absolute/path/to/mcp-code-context/dist/index.js"]
    }
  }
}

Amazon Q / Other MCP Clients

Any MCP-compatible client can use this server. The transport is stdio (JSON-RPC over stdin/stdout). Point your client to node dist/index.js.

Tools

Read Tools

1. get_semantic_repo_map

Generate a compressed architectural overview of an entire repository.

• directoryPath (required) — Path to the repo root
• format (optional) — "xml" (default) or "markdown"

2. read_file_surgical

Read a file, or extract only a specific named symbol. Returns structured suggestions if the symbol is missing.

• filePath (required) — Path to the source file
• symbolName (optional) — Name of a function, class, method, or type
• className (optional) — Scope the symbol to a specific class (to avoid duplicates)

3. analyze_impact

Find all files that depend on a given file.

• filePath (required) — Path to the file being modified
• rootDir (optional) — Repository root (auto-detected)

4. read_file_lines

Read specific line ranges from a file without loading the entire content. More efficient than read_file_surgical for small fragments.

• filePath (required) — Path to the source file
• startLine (optional) — Starting line number (1-indexed)
• endLine (optional) — Ending line number (1-indexed)
• aroundPattern (optional) — Search pattern to find and return surrounding lines
• contextLines (optional) — Number of lines before/after pattern (default: 5)

5. search_code_pattern

Search for code patterns across multiple files with context. Respects .gitignore rules.

• rootDir (required) — Repository root directory
• pattern (required) — Regular expression pattern to search
• fileExtensions (optional) — Array of extensions to search (e.g., [".ts", ".dart"])
• excludeDirs (optional) — Directories to exclude (default: ["node_modules", "dist", "build"])
• showContext (optional) — Include surrounding lines (default: true)
• contextLines (optional) — Number of context lines (default: 3)
• maxResults (optional) — Maximum matches to return (default: 50)

6. rollback_file

Surgically restore a file to a previous state from the automated backup system.

• filePath (required) — Path to the file to restore
• steps (optional) — Number of versions to go back (1-5, default: 1)

7. clean_backups

Remove all backup files for a project to keep the working directory clean.

• projectRoot (required) — Absolute path to the project root

Note: Backups are stored centrally at [project-root]/.mcp-backups/ to keep your project organized.

Write Tools (Phase 1: Preview)

All write tools follow a Two-Phase Workflow:

• Call without token: Returns a unified diff and a confirmationToken.
• Call with token: Set confirm: true and provide the token to apply the changes.

7. write_file_surgical

Replace the full source code of a named symbol in a file.

• filePath (required) — Path to the file
• symbolName (required) — Symbol to replace
• newContent (required) — Replacement code (signature + body)
• confirmationToken (optional) — Token from Phase 1 to apply changes
• confirm (optional) — Set to true to apply
• className (optional) — Scope the symbol to a specific class

8. insert_symbol

Insert new code at a precise location relative to an existing symbol.

• filePath (required) — Path to the file
• code (required) — Code to insert
• anchorSymbol (optional) — Symbol to position relative to
• position (optional) — "before", "after", "inside_start", "inside_end"
• className (optional) — Scope the anchor to a specific class
• confirmationToken, confirm (optional)

9. rename_symbol

Rename a symbol across the entire repository (definition + all usages).

• filePath (required) — File where the symbol is defined
• oldName (required) — Current name
• newName (required) — New name
• rootDir (optional) — Repository root
• confirmationToken, confirm (optional)

10. remove_symbol

Safely remove a symbol from a file with dependency checking.

• filePath (required) — Path to the file
• symbolName (required) — Symbol to remove
• className (optional) — Scope the symbol to a specific class
• force (optional) — Skip dependency check
• confirmationToken, confirm (optional)

Recommended Workflow

• Understand → get_semantic_repo_map to see the architecture
• Read → read_file_surgical with symbol name for specific implementations
• Assess → analyze_impact before modifying shared files
• Edit (Preview) → Call write tools to generate a diff and confirmationToken
• Confim → Call the same write tool with the token and confirm: true to apply
• Recovery → Use rollback_file if something goes wrong after confirmation

Development

# Build
npm run build

# Run read tests (compression + extraction)
npm run build && node dist/tests/test-dart.js && node dist/tests/test-php.js

# Run write tests (replace, insert, rename, remove)
npm run build && node dist/tests/writers/test-write-smoke.js

# Run all tests
npm run build && node dist/tests/test-dart.js && node dist/tests/test-php.js && node dist/tests/writers/test-write-smoke.js

# Development (build + start)
npm run dev

Technical Details

• Transport: stdio (JSON-RPC over stdin/stdout)
• Runtime: Node.js >= 18
• Protocol: Model Context Protocol
• AST Engines: web-tree-sitter@0.25.1 (WASM) for TypeScript/JS/Python/PHP/Dart
• Language Grammars: tree-sitter-wasms@0.1.13 (ABI v15)
• Ignore Engine: ignore npm package (full .gitignore spec support)
• Safety Features: Mandatory two-phase confirmation, rolling 5-version backups, fuzzy matching, dependency checking, surgical restoration.
• Portability: 100% WASM - no native dependencies, works on all platforms

License

MIT