AmazingMCP — MCP Server for .NET / C# Codebases

An MCP server that gives AI agents deep understanding of C# codebases via Roslyn — type search, dependency graphs, usage analysis, and architecture overviews, all from a live in-memory compilation.

Installation

dotnet tool install -g HoldMyCoolantMeatbag.AmazingMCP

Requires .NET 10 SDK.

MCP Tools

Tool	Description
query_symbol	Find types, members (methods, properties, fields), extension methods, constants, and enum values across the solution and NuGet packages
get_type_details	Full type info: properties, methods, base types, nested types (including NuGet)
query_usages	Find all usages of a type across the solution: method calls, constructor calls, property/field read and write, generic arguments and constraints, return types, parameter types, inheritance, nameof, typeof, is/as. Supports predicate filtering and scan scope control
read_cs_file_digest	Token-efficient entry point for large .cs files (hundreds or thousands of lines): returns a structural outline — types and members with line numbers, no implementations. Use this first, then fetch only the members you need with read_large_cs_file
read_large_cs_file	Read specific member implementations from a .cs file by name filter — use after read_cs_file_digest to load only what's relevant instead of the entire file
decompile_type	Decompile any type from a NuGet assembly to C# source — no external tools required, ILSpy is built in
code_lens	Resolve fully-qualified types for any line range in a .cs file: local variables, field/property types, method call signatures, object creations, and declarations — all from the Roslyn semantic model
get_project_design	High-level architecture map: abstraction groups by namespace and inter-group dependencies
get_project_design_details	Detailed view of abstractions and implementations for specified namespaces (supports * wildcard)

Features

• One server, any number of solutions — start it once and point it at any project per call, no restart needed when switching between solutions.
• Live in-memory compilation — opens .sln/.slnx via MSBuild Workspaces and compiles all projects in memory. All tools run against a real Roslyn semantic model, not text search.
• Incremental cache — workspace is cached with file watchers. .cs changes trigger incremental recompilation; .csproj/.sln changes invalidate the full cache. First call per solution is slow; subsequent calls are instant.
• NuGet-aware — NuGet types are fully resolved and searchable alongside source types. query_symbol, get_type_details, and decompile_type work on any referenced package.

Usage

AmazingMCP <options>

# example:
AmazingMCP --urls=http://localhost:7777 --Symbol:QueryOutputLineLimit=50 --ReadCs:ReadOutputMaxLength=50000

# see all options:
AmazingMCP --help

The server starts on http://localhost:7777 by default.

Command-line options

Option	Default	Description
--urls	http://localhost:7777	Listening URL
--Symbol:QueryOutputLineLimit	100	Max output lines for query_symbol
--ReadCs:ReadOutputMaxLength	20000	Max output characters for read_large_cs_file
--ProjectDesign:DetailsOutputMaxLength	30000	Max output characters for get_project_design_details
--ProjectDesign:DetailsXmlDocSummaryMaxLength	2000	Max XML doc summary characters in get_project_design_details
--QueryUsages:QueryMatchLimit	200	Max usage matches for query_usages
--Diagnostics:IncludeExceptionDetails	false	Include full exception details in tool error responses (for diagnostics)
--DisabledTools	(none)	Comma-separated list of tool names to disable (e.g. code_lens,get_project_design)

MCP Client Configuration

Add to your MCP client config (Claude Desktop, JetBrains AI, Kiro, etc.):

{
  "mcpServers": {
    "AmazingMCP": {
      "type": "http",
      "url": "http://localhost:7777"
    }
  }
}

Then start the server manually in your terminal:

AmazingMCP --urls=http://localhost:7777 <other options>

Or add a launcher entry so the client starts the server automatically:

{
  "mcpServers": {
    "AmazingMCP": {
      "type": "http",
      "url": "http://localhost:7777"
    },
    "AmazingMCP Launcher": {
      "command": "AmazingMCP",
      "args": ["--urls=http://localhost:7777"]
    }
  }
}

Documentation

• QuerySymbol — type and member search
• QueryUsages — usage search
• CodeLens — type resolution for a code span
• FileStructure — token-efficient file reading
• DecompileType — NuGet assembly decompilation
• ProjectDesign — architecture overview tool
• DependencyMap — dependency map

Contributing

PRs and issues are welcome. Please open an issue before submitting a large change.

git clone https://github.com/remleo/AmazingMCP
cd AmazingMCP
dotnet build
dotnet test

License

MIT