mcp-digger

mcp-digger

Code context for AI coding agents. Progressive, on-demand access to your internal .NET / NuGet package source — agents browse, search, and read private C# libraries autonomously, with zero workspace pollution.

⚠ Scope: .NET / C# only. mcp-digger indexes NuGet-style repos containing .csproj packages and .cs source files. It is not a general-purpose source indexer — other languages (TypeScript, Python, Java, Go, etc.) are out of scope.

✨ Why

Public NuGet packages have documentation ecosystems — API references, tutorials, community Q&A. Tools like context7 serve that well.

Internal .NET packages often have source code as their primary documentation. mcp-digger turns that source into structured, searchable, token-efficient context that any MCP-compatible agent can consume — bridging the documentation gap in private C# library ecosystems.

Without it:

• 🐢 Slow context gathering — git clone + find + grep + cat chains burn tokens on infrastructure before useful context is retrieved.
• 🔍 No semantic search — file system tools find text, not API surfaces. "Every type implementing this interface" means writing extraction scripts on demand.
• 💸 Token waste — agents read whole files when a single method signature would do.
• 🖱 Permission click fatigue — dozens of shell-command approvals per session.
• 🧹 Workspace noise — referenced repos pollute file search, git status, and the agent's context window.

With it:

• ✅ Correct code on the first try — real signatures, generic constraints, interface contracts, base class patterns.
• ⚡ Self-service context — point the agent at your NuGet repos once; it browses, searches, and reads autonomously.
• 🪙 Progressive disclosure — 200-token overview before 5,000 tokens of source. Most questions resolve at L1 or L2.
• 🧼 Zero workspace pollution — managed clones live outside your project tree.
• 🌐 Any Git host — GitHub, GitLab, Azure DevOps, Bitbucket, self-hosted — HTTPS or SSH.

🛠 How it works

Ten purpose-built tools, escalating from broad to deep. The agent picks the cheapest tool that answers its question.

                                                           ┌─→ 📦 dig_package_overview ─┐
                                                           │   (docs, key types)        │
   🩺 dig_status  →  📋 dig_list  →  📖 dig_repo_overview  ┤                            ├─→  🔎 dig_lookup     →  📄 dig_file
   (health)          (discover)      (README + summaries)  │                            │   (symbol → file)       (full source)
                                                           ├─→ 📁 dig_package_files ────┤
                                                           │   (file listing)           │
                                                           └────────────────────────────┴─→  📝 dig_signatures
                                                                                            (stripped API)

   Operational:  🔄 dig_refresh   (force cache invalidation, on demand)
   Bootstrap:    🌱 dig_init      (only when no config exists)

🧰 Tools (10)

Tier	Tool	What it does
Health	🩺 dig_status	Config summary, connectivity check per repo, index health stats
Discovery	📋 dig_list	Lists configured repos + their packages with one-line .csproj summaries
L1 Overview	📖 dig_repo_overview	Repo README.md (filtered to architecture sections) + package count
L1 Overview	📦 dig_package_overview	Package docs, key interfaces, abstract classes, file count
L1 Overview	📁 dig_package_files	.cs file listing for a package, with directory summary header
L2 Search	🔎 dig_lookup	Indexed symbol search — symbol, implements, or references mode. Cross-package supported.
L2 Search	📝 dig_signatures	Stripped C# public API surface filtered by keyword (no method bodies)
L3 Source	📄 dig_file	Full source of a single file (capped at 1 MB)
Operational	🔄 dig_refresh	Force-rebuild caches for one or all repos
Bootstrap	🌱 dig_init	Creates starter .digger/config.json (registered only when no config is found)

Search modes for dig_lookup:

Mode	Finds
symbol (default)	Type/method declarations matching a name substring
implements	Classes/structs implementing an interface or extending a base class
references	Files referencing a given type name (word-boundary, case-sensitive)

🚀 Quick start

Install

npm install -g mcp-digger
# or run directly
npx mcp-digger

Requires Node.js 20+, git on PATH, and a .NET / C# source repo (NuGet packages with .csproj + .cs sources).

Minimal config

Create .digger/config.json in your workspace root:

{
  "repos": [
    {
      "name": "my-libraries",
      "url": "https://github.com/org/shared-libs.git",
      "packageFilter": "MyCompany.*",
      "auth": {
        "strategy": "pat",
        "PAT-EnvVarName": "GIT_PAT"
      }
    }
  ]
}

Don't have a config yet? Start the server, then call dig_init to scaffold one.

Agent setup

Claude Code

Add to .claude/settings.json or project settings:

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

Codex CLI

Add to ~/.codex/config.toml (or .codex/config.toml for project-scoped):

[mcp_servers.mcp-digger]
command = "npx"
args = ["-y", "mcp-digger"]

Claude Desktop

Add to claude_desktop_config.json:

• Windows: %APPDATA%\Claude\claude_desktop_config.json
• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json

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

VS Code

Add to .vscode/mcp.json (workspace) or your user mcp.json:

{
  "servers": {
    "digger": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "mcp-digger"]
    }
  }
}

Cursor

Add to .cursor/mcp.json (project) or ~/.cursor/mcp.json (global):

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

Verify

Once connected, ask your agent to call dig_status — it reports config validation, per-repo connectivity, and index health.

⚙ Configuration

Repos & packages

A repos[] entry has three ways to declare packages:

Option	Behavior
"packages": ["A", "B"]	Explicit list — these packages plus any local sibling project they pull in via <ProjectReference> (transitive, sibling-only).
"packageFilter": "MyCompany.*"	Wildcard — narrows to packages matching the prefix, found via .sln/.slnx/Directory.Packages.props workspace scan. Follows transitive ProjectReference links automatically.
(omit both)	Auto-discover all non-test .csproj directories under sourceRoot (recursive — nested layouts supported).

sourceRoot defaults to "src" — set it to whichever directory holds your package folders. The walk is recursive, so nested layouts like src/Group/Foo/Foo.csproj are picked up.

Branch tracking

By default, managed clones use the repo's default branch. Pin to a specific one:

{
  "repos": [
    {
      "name": "my-libraries",
      "url": "https://github.com/org/shared-libs.git",
      "branch": "develop"
    }
  ]
}

The branch is used for both initial clone and subsequent fetches. Only applies to managed clones — for local repos, you control the checked-out branch yourself.

Local repos (Mode B)

Skip managed cloning when the repo is already on disk. The local path is read-only — mcp-digger never fetches or modifies it.

{
  "localRepos": {
    "my-libraries": "C:/repos/shared-libs"
  },
  "repos": [
    {
      "name": "my-libraries",
      "sourceRoot": "src"
    }
  ]
}

Auth strategies

Strategy	Behavior
auto (default)	Try unauthenticated, fall back to PAT if set
pat	Always use PAT (fatal if not set)
none	Never authenticate

PATs can be inline ("PAT": "...") or via environment variable indirection ("PAT-EnvVarName": "MY_TOKEN"). The .env file in your workspace root is loaded automatically — values containing # should be quoted.

Environment variables

Variable	Default	Purpose
DIGGER_CONFIG	.digger/config.json	Override config file path
MANAGED_SOURCE_DIR	.digger/source	Override managed clone directory
CACHE_DIR	.digger/cache	Override cache directory

Secrets (PAT values) belong in .env or the real environment — never as env vars in this table.

🩺 Diagnostics & recovery

Symptom	First call	Then
Connection / auth issues	dig_status	Reports auth attempts, exact error, actionable hints
"No matches" but you expect some	dig_refresh <repo>	Force-rebuilds index, picks up new extraction logic
Server starts but no tools visible	dig_status	If unconfigured, only dig_status + dig_init are registered
Need a config from scratch	dig_init	Scaffolds .digger/config.json (atomic — won't overwrite existing)

Debug log

Enable debug logging in your config:

{ "debug": true, "repos": [...] }

Logs go to .digger/debug.log (capped at 5 MB, auto-truncated). Critical errors and crash output land in .digger/error.log.

💬 Feedback

Tried mcp-digger on your codebase? Share what worked, what broke, what's missing in GitHub Discussions. Bug reports go in Issues.

📜 License

MIT License — see LICENSE.