mcp-injector

AI coding assistants often fail because they retrieve the wrong context. On a large codebase, blindly dumping raw files into the prompt leads to hallucinations, slow responses, and high API costs.

Foldwork fixes this. It is a deterministic repository understanding engine that pre-indexes your entire codebase into a local SQLite catalog. It acts as the Context Layer for your IDE, serving exactly the functions the AI needs—no more, no less—maximizing the first-try success rate and reducing token usage by 41-89%.

By combining AST body folding (which strips out function bodies while preserving signatures) with canonical determinism (which guarantees byte-identical outputs to maximize Anthropic's KV cache hits), Foldwork transforms massive enterprise monorepos into lightweight, cache-friendly payloads. This drastically reduces token consumption, cuts API costs by up to 90%, and eliminates context window overflow.

No cloud. No telemetry. Runs entirely on your machine.--

Real-World Codebase Context Benchmarks

Estimate the impact of AST code compression on large open-source repositories (calculated at $2.00 / million input tokens for Claude Sonnet 5):

Numbers are reproducible. Run the open-source benchmark tool on any public repository:
mcp-benchmark repository

Related MCP server: Headless Codebase Indexer

What It Looks Like

Run mcp-benchmark on your own project to see your exact savings before installing anything:

mcp-benchmark ./your-project

════════════════════════════════════════════════════════════════════════════════
  mcp-injector Benchmark — context
  Tier 3 compression  |  $2.00/1M tokens  |  2026-07-15T12:00:00Z
════════════════════════════════════════════════════════════════════════════════

FILE                                          RAW TOKENS    COMPRESSED     SAVED   COST SAVED*
──────────────────────────────────────────────────────────────────────────────────────────
cmd/license-gen/main.go                            3,633           214       94%       $0.0072
main.go                                           17,555         1,917       89%       $0.0347
website/api/webhook.go                             2,682           295       89%       $0.0053
main_test.go                                       1,576           353       78%       $0.0031
──────────────────────────────────────────────────────────────────────────────────────────
TOTAL (4 files)                                   25,446         2,779     89.1%       $0.0503

  * Based on $2.00 / 1M input tokens

  💡 Running this codebase through Claude 10×/day costs $0.51/day raw.
     With mcp-injector:  $0.01/day.  You save $0.50/day ($15/month).

Tools

get_project_map

Returns a compressed structural overview of the workspace. Function bodies are folded and replaced with placeholders to reduce token usage.

• tier (integer, optional): Compression tier to apply (default: 2).

• unfolded_files (array of strings, optional): Workspace-relative paths or glob patterns for files to serve at full resolution (uncompressed).

• path_prefixes (array of strings, optional): Scope the project map to specific microservices or packages, drastically reducing payload bloat.

• git_context: always includes current branch, changed files, and recent commits in the response.

• secrets_redacted: count of credentials automatically redacted before sending to Claude.

Example call:

{
  "tool": "get_project_map",
  "arguments": {
    "tier": 3,
    "unfolded_files": ["src/auth/handler.go", "**/*_test.go"],
    "path_prefixes": ["src/auth/"]
  }
}

injector_retrieve

Retrieves the full uncompressed source of a file from the local cache.

• path (string, required): The workspace-relative path of the file to retrieve.

• retrievalKey (string, optional): The SHA-256 retrieval key returned in a prior compressed payload.

• start_line (integer, optional): 1-indexed start line for range retrieval.

• end_line (integer, optional): 1-indexed end line for range retrieval.

• expand_graph (boolean, optional): Resolves and appends cross-file dependencies (limited to 50 1st-degree dependencies).

injector_search

BM25-ranked full-text symbol search over the local SQLite catalog. Supports FTS5 boolean logic (e.g., user AND (auth OR login)).

• query (string, required): FTS5 query string (bare terms, "phrase", prefix*).

• limit (integer, optional): Maximum results (default: 20).

• search_paths (array of strings, optional): Scope search to specific isolated directories.

injector_diagram

Generates a Mermaid sequence diagram for a given symbol by traversing its outbound dependencies (halts after 500 nodes).

• symbol (string, required): The exact symbol name.

• max_depth (integer, optional): Maximum traversal depth (default: 3).

• include_primitives (boolean, optional): Include basic types (String, boolean) and framework boundaries.

injector_regex_search

Fallback for exact literal or regex searches against file contents. Bypasses FTS5 tokenization.

• query (string, required): The string or regex pattern to search for.

• is_regex (boolean, optional): Treats query as extended regex (-E).

injector_write_file

Write a full file to disk. CRITICAL: Prevents data loss by intercepting and rejecting payloads containing compressed fold markers.

injector_blast_radius

Analyzes the architectural impact of changing a symbol by traversing the dependency graph. Supports inbound and outbound directional traversal.

injector_git_context

Integrates with local Git history to surface commit context, authorship, and code evolution directly into the LLM context.

injector_inspect_table

Enables direct database introspection capabilities. Currently supports PostgreSQL and MySQL. CRITICAL: You must start the daemon with the FOLDWORK_DB_DSN environment variable set to your database connection string (e.g. postgres://user:pass@localhost:5432/dbname) to activate this tool.

injector_clear_cache

Wipes the SQLite index cache and triggers a clean cold-start full re-index.

injector_stats

Returns index status, current compression ratio, total files indexed, and cache hit rate.

injector_sync (Deprecated)

Read tools automatically wait for pending indexing implicitly. You never need to manually call this tool.

Quick Install

Install the daemon locally and configure your IDEs:

curl -fsSL https://foldwork.dev/install | sh

Automatically configures Claude Desktop, Cursor IDE, VS Code, Devin Desktop, and Antigravity.

Getting Started

Step 1: Check if your project qualifies for the free tier

Run the benchmark CLI on your project to see your token savings and line count:

mcp-benchmark ./your-project

If your project is under 50,000 lines, mcp-injector is completely free. The benchmark output shows your exact line count.

Step 2: Install the daemon

curl -fsSL https://foldwork.dev/install | sh

The installer auto-detects Claude Desktop, Cursor, VS Code, Devin Desktop, and Antigravity and writes the MCP config automatically. You should see output like:

* mcp-injector v0.2.0 installed to /usr/local/bin/mcp-injector
* Claude Desktop configured
* Cursor configured
Restart your IDE and mcp-injector will be active.

Step 3: Restart your IDE

The MCP server starts automatically when your IDE launches. No separate daemon process to manage.

Step 4: Verify it is working

In Claude Code or Cursor, ask Claude:

"Use get_project_map to show me the structure of this project"

Claude will call the mcp-injector tool and return a compressed map of your entire codebase. If you see module names, entry points, and dependency information - it is working.

Step 5: Get the full source when needed

When Claude needs to see the complete implementation of a compressed function, it automatically calls injector_retrieve. You can also trigger this explicitly:

"Show me the full implementation of UserService.java"

Claude will fetch the uncompressed source from the local cache.

Editing Code: You MUST use the injector_write_file tool to edit code. If Claude tries to write back folded placeholders into your source code, the daemon will hard-reject the payload to protect you from data loss.

Step 6: Check your savings

injector_stats

Or ask Claude directly: "Call injector_stats and tell me my current token savings."

Agent Use Cases & Advanced Usage

Now that your AI has deterministic tools to search, traverse, and retrieve code, you can ask it high-level architectural questions that usually fail on raw codebases:

• Trace authentication flow — Ask the agent to map out your login sequence; it will use injector_retrieve with expand_graph=true to traverse through middleware, validation, and database layers.

• Find dead code — The agent can leverage injector_blast_radius (inbound traversal) to identify unused functions and isolated structs.

• Generate architecture diagrams — Tell your AI to "Generate a Mermaid diagram for this workflow"; it uses injector_diagram to instantly draw the entire outbound execution sequence.

• Understand dependency graphs — Use injector_blast_radius to see exactly what services or packages rely on a specific core module.

• Locate implementations — The agent uses injector_search (BM25 full-text indexing) to find exact function definitions across millions of lines of code.

• Refactor safely — Before making a breaking change, the agent checks injector_blast_radius to see every caller that will be impacted.

• Review pull requests — Instruct the agent to analyze your uncommitted changes or branch diff. It uses injector_git_context to understand recent commits and author intent alongside the code.

• Navigate large monorepos — get_project_map gives the AI a compressed, birds-eye view of your entire architecture, allowing it to drill down into specific microservices using path_prefixes.

Inspecting specific files uncompressed

Sometimes you need Claude to see the exact implementation of a file while keeping the rest compressed. Use the unfolded_files parameter:

In your MCP call or by asking Claude:

"Get the project map but show me src/auth/handler.go at full resolution"

This passes "unfolded_files": ["src/auth/handler.go"] to get_project_map. That file is served raw; everything else stays compressed.

Glob patterns work too:

• "**/*_test.go" - all test files uncompressed

• "src/auth/*.go" - all files in a directory uncompressed

Switching branches

mcp-injector installs a post-checkout git hook when it first runs. Branch switching automatically triggers a full re-index. You will see this in the daemon logs:

[mcp-injector] Branch switched to feature/auth-refactor, re-indexing...
[mcp-injector] Re-index complete in 4.2s (47,293 lines indexed)

Security First: Zero-Leak Guarantee

Enterprise security teams often block AI coding tools because developers accidentally leak sensitive credentials in their context window.

mcp-injector solves this locally. The daemon includes a built-in Shannon entropy filter that analyzes all AST strings and comments in real-time. If it detects high-entropy strings (like AWS Access Keys, SSH private keys, or database passwords), it dynamically redacts them as [REDACTED: high entropy] before they ever leave your machine. Your API credentials are never sent to Anthropic.

If your codebase has a hardcoded API key or AWS credential, the get_project_map response will include:

"secrets_redacted": 2,
"files_with_redactions": ["config/db.go", "scripts/deploy.sh"]

The actual values are replaced with [REDACTED: high entropy]. Variable names are preserved so Claude still understands the code structure.

Manual MCP configuration

If the auto-installer does not detect your IDE, add this to your MCP config manually:

{
  "mcpServers": {
    "mcp-injector": {
      "command": "/usr/local/bin/mcp-injector",
      "env": {
        "MCP_WORKSPACE": "/absolute/path/to/your/project",
        "FOLDWORK_DB_DSN": "postgres://user:pass@localhost:5432/dbname"
      }
    }
  }
}

Note: VS Code supports "${workspaceFolder}", but Claude Desktop, Cursor, and Devin Desktop require a hardcoded absolute path to your project.

Config file locations:

• Claude Desktop (Mac): ~/Library/Application Support/Claude/claude_desktop_config.json

• Claude Desktop (Windows): %APPDATA%\Claude\claude_desktop_config.json

• Claude Desktop (Linux): ~/.config/Claude/claude_desktop_config.json

• Cursor: ~/.cursor/mcp.json

• VS Code: .vscode/mcp.json

• Devin Desktop: ~/.codeium/windsurf/mcp_config.json

• Antigravity: ~/.gemini/antigravity/mcp_config.json

How It Works

• Incremental Parsing: Foldwork scans your repository instantly using a single-pass AST parser, identifying all interfaces, classes, and function signatures without blocking.

• Graph Generation: It deterministically builds two structures: a Symbol Graph for precise definitions, and a Dependency Graph tracking outbound caller/callee relationships.

• Local Catalog: The graphs are durably stored in a local SQLite FTS5 catalog. Indexing happens exactly once per file change, meaning zero overhead during AI prompts.

• MCP Serving: Your AI agent securely communicates with Foldwork via the Model Context Protocol, fetching sub-graphs in milliseconds without the code ever leaving your machine.

• Branch-Aware & Deterministic: Switching branches triggers automatic incremental re-indexing via git hooks. By guaranteeing byte-identical outputs across runs, Foldwork maximizes Claude's KV prompt caching hits.

Supports: Go, Python, TypeScript, JavaScript, Java, C++, C, C#, Rust.

Pricing Tiers

• Free Tier: Workspaces under 50,000 total source lines (all tools and features fully active).

• Pro Tier ($12/month or $99/year): Unlocks unlimited workspace sizes and high-speed incremental diff indexing.
  Activate Pro at foldwork.dev

Check your ROI (Savings Dashboard)

You can run mcp-injector status in your terminal at any time. This CLI dashboard visually proves your exact token savings and estimated dollars saved by comparing your raw codebase tokens against the AST-compressed tokens in real-time.

Security

mcp-injector automatically redacts secrets and credentials before they reach Claude's context window:

• AWS access keys, GitHub PATs, Stripe secret keys

• JWT tokens and bearer tokens

• High-entropy strings detected via Shannon entropy analysis

• Private key headers (-----BEGIN RSA PRIVATE KEY-----)

• Air-Gapped Ready: Pro license validation uses strictly offline Ed25519 cryptography. The daemon never makes an outbound network request, even to verify your subscription.

Redacted content is replaced with [REDACTED BY MCP-INJECTOR]. A count of redactions is included in the get_project_map response so you always know what was protected.

Your code never leaves your machine. Redaction happens locally before compression, and is always-on - it cannot be disabled.

Uninstall

To remove mcp-injector completely:

# Remove binary
sudo rm /usr/local/bin/mcp-injector

# Remove index cache and logs
rm -rf ~/.mcp-injector/

# Remove from IDE MCP config (edit manually):
# Claude Desktop (Linux): ~/.config/Claude/claude_desktop_config.json
# Claude Desktop (macOS): ~/Library/Application Support/Claude/claude_desktop_config.json
# Cursor: ~/.cursor/mcp.json
# VS Code: .vscode/mcp.json
# Devin Desktop: ~/.codeium/windsurf/mcp_config.json
# Antigravity: ~/.gemini/antigravity/mcp_config.json
# (Remove the "mcp-injector" entry from mcpServers)

What Gets Redacted

mcp-injector automatically redacts the following before your code reaches Claude:

Redacted values are replaced with [REDACTED BY MCP-INJECTOR]. File paths and variable names are never redacted - only the values.

License

Commercial. Free tier available. Source code not public.
Support Contact: foldwork@proton.me