Dev Context MCP Server

Dev Context MCP is a .NET 10 Model Context Protocol server that gives coding agents grounded, version-aware access to internal NuGet packages and company documentation.

It indexes package metadata, README files, XML documentation, packaged text files, public .NET symbols, dependencies, target frameworks, and an optional documentation directory. Agents can then discover libraries, select an indexed version, search documentation, inspect real API signatures, and open the exact source material behind each answer.

The system never loads or executes package assemblies. Retrieval is served entirely from a local SQLite/FTS5 index.

Why This Project Exists

Coding agents often know public libraries but lack reliable context for private packages, generated API clients, environment-specific builds, and company standards. Dev Context MCP turns those sources into a small, deterministic MCP surface:

Package discovery by exact ID or implementation concept.
Explicit environment and semantic-version selection.
Documentation search isolated to one package version.
Metadata-only lookup of public types and members.
Stable citations that can be opened as MCP resources.
Machine-readable ok, not_found, and insufficient_evidence outcomes.

Generated clients do not need special handling. If a client is published as a NuGet package with public assemblies and useful documentation, it follows the same indexing and retrieval path as any other package.

How It Works

Index production and MCP retrieval are separate processes:

flowchart LR
    Feeds[NuGet feeds or local package folders]
    Docs[Company documentation folder]
    Indexer[DevContextMcp.Indexer]
    Database[(SQLite and FTS5)]
    Server[DevContextMcp.Server]
    Client[MCP client or coding agent]

    Feeds --> Indexer
    Docs --> Indexer
    Indexer -->|only writer| Database
    Database -->|read only| Server
    Client -->|stdio or Streamable HTTP| Server

The one-shot Indexer reads configured sources and package-policy files.
It safely downloads or opens selected .nupkg files.
It extracts metadata, documents, and symbols without executing package code.
It atomically publishes changed content to SQLite and updates FTS5.
The Server opens the same database read-only and exposes MCP tools and resources.

Run only one Indexer process against a database at a time. The Server can stay independent of feeds and credentials because it never refreshes data itself.

Solution was designed and implemented with Codex AI agent using specs and plans defined in design folder.

Configuration:

Indexer Configuration — how to set up indexing sources, package policies, and documentation paths.
Server Configuration — how to configure transport (stdio or HTTP) and logging.

Demo

Repository contains Demo Indexer data for Demo Project. The demo project design and implementation were AI-generated using DevContext MCP server. The demo folder contains:

Demo Applications — .NET applications that generate demo NuGet packages:

Demo.Cities — generates prod and qa versions of a sample NuGet package.
OpenMeteo.Api.Client — OpenAPI-generated client library.

Demo Data — source material for indexing:

NuGets Repo — contains .nupkg files organized by prod and qa feeds (paths defined in Indexer Configuration).
Indexer — documentation files and package policies for indexing.

Quick Start

Prerequisites

The .NET SDK selected by global.json, currently .NET SDK 10.0.301 with latest-patch roll-forward.
Internet access when restoring packages and when indexing the bundled public NuGet example.

1. Build and test

dotnet build .\DevContextMcp.slnx
dotnet test .\DevContextMcp.slnx

2. Build the local index

The checked-in Indexer configuration uses:

NuGet.org for Formula.SimpleRepo.
Local prod and qa feeds under demo/data/nuget-repos.
Package policies under demo/data/indexer/nugets.
Company documents under demo/data/indexer/company-docs.

Run the Indexer:

dotnet run --project .\src\DevContextMcp.Indexer\DevContextMcp.Indexer.csproj

The demo database is created at database/docs.db.

Re-running the command is safe. Content hashes prevent unchanged package data from being rewritten, while index-run history records each execution.

3. Start the MCP server

Run the server:

dotnet run --project .\src\DevContextMcp.Server\DevContextMcp.Server.csproj

The checked-in development configuration starts stateless Streamable HTTP at:

http://127.0.0.1:2222/mcp

HTTP is deliberately restricted to an unauthenticated loopback http:// address. It is suitable for local development, not shared-network deployment. Logs are written to standard error and to the configured Serilog file sink.

4. Connect MCP Inspector

For the default HTTP configuration, start the Server and then run:

npx -y @modelcontextprotocol/inspector

Choose Streamable HTTP and connect to http://127.0.0.1:2222/mcp.

Try this workflow after connecting:

Call resolve_library with Demo.Cities.
Pass a returned ID such as nuget:prod/Demo.Cities to list_versions.
Call query_docs or get_symbol with the selected version.
Open a returned nuget:// citation under Resources.
Query docs:company-docs for the bundled company-document examples.

MCP Surface

Tools

| Tool | Purpose | Important inputs | | --- | --- | --- | | resolve_library | Finds indexed NuGet packages or company documentation by ID, name, or concept. | query, environment, includePrerelease, limit | | list_versions | Lists indexed package versions and identifies the recommended version. | libraryId, includePrerelease | | query_docs | Searches version-scoped package evidence or company documents. | libraryId, question, version, projectVersion, targetFramework, maxResults | | get_symbol | Finds a public type or member and returns its indexed signature and XML documentation. | libraryId, symbol, version, projectVersion, targetFramework |

get_symbol accepts fully qualified, simple, or partial names. If a lookup is ambiguous, it returns bounded candidates instead of silently choosing one. Symbol lookup is not supported for docs:company-docs.

Library IDs

Discovery returns stable IDs:

nuget:prod/Demo.Cities
nuget:qa/Demo.Cities
docs:company-docs

An environment-qualified NuGet ID never falls back to another environment. Legacy IDs such as nuget:Demo.Cities use the configured environment and source order.

Company documentation is one versionless library. query_docs and resource reads apply to it; NuGet version and symbol operations do not.

Resources and citations

Tool evidence points to read-only MCP resources:

nuget://{source}/{packageId}/{version}/artifact/{path}
nuget://{source}/{packageId}/{version}/symbol/{qualifiedName}
docs://company-docs/{path}

Opening a resource reads the exact indexed artifact or symbol. The Server does not contact a NuGet feed during retrieval.

Version Selection

For query_docs and get_symbol, one version is selected in this order:

Exact version from the tool request.
Exact projectVersion supplied as calling-project context.
Environment-qualified version selection entry.
Package-wide version selection entry.
Latest indexed, listed stable version.
Latest indexed, listed prerelease when prereleases are allowed.

The selected version must already be in the local index. Evidence from different package versions is never combined.

Example: If Demo.Cities has indexed versions 1.0.0, 1.1.0 (stable), and 2.0.0-beta (prerelease):

A tool request with version: "1.0.0" uses 1.0.0.
No explicit version and latest stable returns 1.1.0.
If includePrerelease: true and no explicit version, returns 2.0.0-beta.

Indexed Content and Safety

For each selected NuGet version, the Indexer stores:

Package identity, title, description, authors, tags, URLs, and publication state.
Dependencies and target frameworks.
Markdown, text, and XML documentation.
Public symbols from assemblies under ref/ and lib/.
Content hashes, searchable document chunks, and run diagnostics.

Package archives are treated as untrusted input. Processing enforces package size, document size, archive entry count, extracted-size, and compression-ratio limits. Paths are validated against traversal, and assemblies are inspected through metadata APIs rather than loaded into the runtime.

SQLite publication is transactional. A failed package refresh preserves the last successfully indexed data. The Server applies query timeouts, result limits, response budgets, and citation-safe URI encoding.

Do not put feed credentials or API tokens in package-policy files or the checked-in settings. Source authentication is intentionally isolated behind an infrastructure interface for future approved credential providers.

MCP Servers