MCPSharp MCP — Use Cases, Install & Live Demo

Why use it

Key features

[McpTool] / [McpResource] / [McpParameter] attributes — method-level API
Automatic JSON-RPC, parameter validation, type conversion
XML doc extraction → tool descriptions
Integrations with Microsoft.Extensions.AI and Semantic Kernel
Dynamic tool registration for runtime-defined tools
Also ships a C# MCP client for calling other MCP servers

Live Demo

What it looks like in practice

mcpsharp.replay ▶ ready

0/0

Install

Pick your client

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

{
  "mcpServers": {
    "mcpsharp": {
      "command": "dotnet",
      "args": [
        "add",
        "package",
        "MCPSharp"
      ],
      "_inferred": false
    }
  }
}

Open Claude Desktop → Settings → Developer → Edit Config. Restart after saving.

~/.cursor/mcp.json · .cursor/mcp.json

{
  "mcpServers": {
    "mcpsharp": {
      "command": "dotnet",
      "args": [
        "add",
        "package",
        "MCPSharp"
      ],
      "_inferred": false
    }
  }
}

Cursor uses the same mcpServers schema as Claude Desktop. Project config wins over global.

VS Code → Cline → MCP Servers → Edit

{
  "mcpServers": {
    "mcpsharp": {
      "command": "dotnet",
      "args": [
        "add",
        "package",
        "MCPSharp"
      ],
      "_inferred": false
    }
  }
}

Click the MCP Servers icon in the Cline sidebar, then "Edit Configuration".

~/.codeium/windsurf/mcp_config.json

{
  "mcpServers": {
    "mcpsharp": {
      "command": "dotnet",
      "args": [
        "add",
        "package",
        "MCPSharp"
      ],
      "_inferred": false
    }
  }
}

Same shape as Claude Desktop. Restart Windsurf to pick up changes.

~/.continue/config.json

{
  "mcpServers": [
    {
      "name": "mcpsharp",
      "command": "dotnet",
      "args": [
        "add",
        "package",
        "MCPSharp"
      ]
    }
  ]
}

Continue uses an array of server objects rather than a map.

~/.config/zed/settings.json

{
  "context_servers": {
    "mcpsharp": {
      "command": {
        "path": "dotnet",
        "args": [
          "add",
          "package",
          "MCPSharp"
        ]
      }
    }
  }
}

Add to context_servers. Zed hot-reloads on save.

claude mcp add mcpsharp -- dotnet add package MCPSharp

One-liner. Verify with claude mcp list. Remove with claude mcp remove.

Use Cases

Real-world ways to use MCPSharp

Expose existing C# services as MCP tools

👤 .NET shops with internal libraries they want AI agents to call ⏱ ~30 min intermediate

When to use: You have a working business library in C# and need to make it agent-accessible.

Prerequisites

.NET 8+ SDK — https://dotnet.microsoft.com/download
MCPSharp package — dotnet add package MCPSharp

Flow

Decorate methods

Add [McpTool] to the public methods I want exposed in my OrdersService. Keep signatures; let MCPSharp validate.✓ Copied

→ Attributes applied, XML docs used as descriptions
Start the server

Add a Program.cs entry point that calls MCPServer.StartAsync("orders", "1.0.0").✓ Copied

→ Runs via dotnet run; MCP clients can discover tools
Wire into Claude Desktop

Emit a claude_desktop_config.json snippet that launches my dotnet binary.✓ Copied

→ Config block with command=dotnet args=[run --project, path]

Outcome: An MCP server your C# services power, with little new code.

Pitfalls

Returning large objects without shaping them — Return DTOs — don't serialize EF entities with nav properties, you'll blow up responses

Combine with: fastmcp

Use MCP tools from a Semantic Kernel agent

👤 Teams building agents with Microsoft Semantic Kernel ⏱ ~45 min intermediate

When to use: You're on SK and want to consume an external MCP server's tools.

Flow

Add the client

Add MCPSharp's client and register the remote server as an SK plugin.✓ Copied

→ Tools appear in the SK plan
Call from a function

Show a chat function that calls one of the remote tools when the user asks.✓ Copied

→ Round-trip: prompt → SK selects tool → MCP call → result in reply

Outcome: Your SK app can consume any MCP server cleanly.

Register tools at runtime from a plugin folder

👤 Teams shipping plugin systems or low-code products ⏱ ~60 min advanced

When to use: Users drop in new tool definitions and you want them available without redeploy.

Flow

Scan the folder

Write a loader that reflects each .dll and registers [McpTool] methods dynamically.✓ Copied

→ Tools appear without changing hard-coded lists
Hot-reload safely

Add AssemblyLoadContext isolation so reloads don't leak.✓ Copied

→ Old assemblies unloaded between reloads

Outcome: Pluggable tool set with proper assembly lifecycle.

Pitfalls

Leaking assemblies with default load context — Use collectible AssemblyLoadContext for isolated reloads

Combinations

Pair with other MCPs for X10 leverage

mcpsharp + fastmcp

Compare .NET vs Python MCP server authoring

Port my Python FastMCP tools to MCPSharp for the existing .NET stack.✓ Copied

mcpsharp + csharp-sdk

Official SDK vs community package — pick what fits

Compare MCPSharp and the official csharp-sdk for my needs.✓ Copied

mcpsharp + azure-ai-gateway

Put the C# MCP server behind Azure AI gateway policies

Front my MCPSharp server with the Azure AI gateway for auth/rate limits.✓ Copied

Tools

What this MCP exposes

Tool	Inputs	When to call
[McpTool]	C# method signature	On every method you want an agent to call
[McpResource]	C# member	When you want to expose readable resources (files/data) not tools
[McpParameter]	method parameter	Mark required params and give parameter descriptions
MCPServer.StartAsync	name, version	Start the server over stdio (or configured transport)
MCPClient	server address	From C# to talk to another MCP server

Cost & Limits

What this costs to run

API quota: None — it's a library
Tokens per call: Depends on your tools; the library itself is tiny
Monetary: Free (MIT-style OSS)
Tip: Shape response DTOs intentionally — big JSON blobs inflate both tokens and latency.

Security

Permissions, secrets, blast radius

Credential storage: Whatever your services use (ASP.NET config, KeyVault, etc.). MCPSharp doesn't own credentials.

Data egress: Transport-dependent (stdio local; HTTP/remote if configured).

[McpTool] exposes whatever the method does. Review each annotated method as if it were a public API — no accidental 'delete everything' tools.

Troubleshooting

Common errors and fixes

Tool not discovered by client

Confirm the method is public, has [McpTool], and the attribute name matches what you call it. Also check the server name passed to StartAsync.

Verify: MCPServer.ListTools() at startup

Serialization exception on return

Return a POCO/DTO; avoid lazy-loaded EF entities and types with cyclic references.

Verify: Unit test serialization with System.Text.Json

Semantic Kernel doesn't see tools

Register the MCP plugin explicitly and confirm the kernel builder is aware; some SK versions require explicit import.

Verify: Log plugins at startup

Alternatives

MCPSharp vs others

Alternative	When to use it instead	Tradeoff
csharp-sdk (official)	You want the official Anthropic/MCP C# SDK	Different ergonomics; watch for feature differences
fastmcp	You prefer Python	Different ecosystem
mcp-agent	You want Python-based agent patterns, not just server authoring	Not .NET

More

Resources

📖 Read the official README on GitHub

🐙 Browse open issues

🔍 Browse all 400+ MCP servers and Skills