MCP

What it does

When your agent uses it

• : .NET MCP servers
• Stdio versus HTTP transport choices
• Capability negotiation
• : unrelated stacks

Example prompts

• “/mcp”

Requirements

• Compatibility (from SKILL.md): Requires the official MCP C# SDK packages (`ModelContextProtocol.Core`, `ModelContextProtocol`, or `ModelContextProtocol.AspNetCore`) on .NET 8+; current guidance targets the v2.2 SDK and MCP 2026-07-28.

Workflow steps

9 steps, taken from the first numbered list in SKILL.md.

1. 1Pick the package and transport first.
2. 2Model the MCP surface explicitly.
3. 3Prefer attribute discovery for straightforward servers.
4. 4For HTTP servers, use the ASP.NET Core transport and map the endpoint directly.
5. 5When consuming a server, use McpClient.CreateAsync(...) and stay capability-aware.
6. 6Treat optional features as negotiated capabilities, not assumptions.
7. 7Keep HTTP guidance current.
8. 8Treat the .NET AI MCP quickstarts as bootstrap examples.
9. 9Respect current error and serialization rules.

What it can do on your machine

Read from SKILL.md and the folder at commit 535dd55. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  No scripts in the folder and no shell commands in SKILL.md (its code samples are csharp and mermaid).

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  Links to these hosts (documentation or services it may open):

  • csharp.sdk.modelcontextprotocol.io
  • github.com
  • modelcontextprotocol.io

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

• Compatibility

  Requires the official MCP C# SDK packages (`ModelContextProtocol.Core`, `ModelContextProtocol`, or `ModelContextProtocol.AspNetCore`) on .NET 8+; current guidance targets the v2.2 SDK and MCP 2026-07-28.

  From compatibility in the SKILL.md frontmatter.

Context cost

MCP loads about 3.5k tokens when it runs, and up to ~8.3k if it reads all its reference files. Until then it costs about 143 tokens; SKILL.md has 1,240 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~143

When it runs · the whole SKILL.md, loaded when a task matches

~3.5k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~8.3k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from managedcode/dotnet-skills at commit 535dd55, republished under its MIT licence (© managedcode). 1,240 words, ~3,516 tokens.

name

mcp

description

Build or consume Model Context Protocol (MCP) servers and clients in .NET using the official MCP C# SDK, including stdio, Streamable HTTP, tools, prompts, resources, and capability negotiation. USE FOR: .NET MCP servers or clients; stdio versus HTTP transport choices; tools, resources, prompts, completions, and capability negotiation. DO NOT USE FOR: unrelated stacks; generic tasks that do not need this specific guidance. INVOKES: inspect the repository context, edit targeted files, and run relevant build, test, lint, or validation commands when changes are made.

compatibility

Requires the official MCP C# SDK packages (`ModelContextProtocol.Core`, `ModelContextProtocol`, or `ModelContextProtocol.AspNetCore`) on .NET 8+; current guidance targets the v2.2 SDK and MCP 2026-07-28.

flowchart LR
    A["Need MCP interoperability in .NET"] --> B{"Role?"}
    B -->|"Expose MCP surface"| C{"Where will it run?"}
    B -->|"Consume an MCP server"| D{"Transport?"}
    C -->|"Local child process"| E["ModelContextProtocol\nAddMcpServer()\nWithStdioServerTransport()"]
    C -->|"Remote HTTP endpoint"| F["ModelContextProtocol.AspNetCore\nAddMcpServer()\nWithHttpTransport()\nMapMcp()"]
    D -->|"stdio"| G["StdioClientTransport\nMcpClient.CreateAsync()"]
    D -->|"HTTP"| H["HttpClientTransport\nAutoDetect or StreamableHttp"]
    E --> I["Register tools/resources/prompts"]
    F --> I
    G --> J["Check ServerCapabilities\nbefore optional features"]
    H --> J

using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using ModelContextProtocol.Server;
using System.ComponentModel;

var builder = Host.CreateApplicationBuilder(args);
builder.Logging.AddConsole(options =>
{
    options.LogToStandardErrorThreshold = LogLevel.Trace;
});

builder.Services
    .AddMcpServer()
    .WithStdioServerTransport()
    .WithToolsFromAssembly();

await builder.Build().RunAsync();

[McpServerToolType]
public static class EchoTool
{
    [McpServerTool, Description("Echoes the message back to the client.")]
    public static string Echo(string message) => $"hello {message}";
}

using ModelContextProtocol.Server;
using System.ComponentModel;

var builder = WebApplication.CreateBuilder(args);

builder.Services
    .AddMcpServer()
    .WithHttpTransport()
    .WithToolsFromAssembly();

var app = builder.Build();
app.MapMcp("/mcp");
app.Run();

[McpServerToolType]
public static class EchoTool
{
    [McpServerTool, Description("Echoes the message back to the client.")]
    public static string Echo(string message) => $"hello {message}";
}

using ModelContextProtocol.Client;
using ModelContextProtocol.Protocol;

var transport = new StdioClientTransport(new StdioClientTransportOptions
{
    Name = "Everything",
    Command = "npx",
    Arguments = ["-y", "@modelcontextprotocol/server-everything"],
});

await using var client = await McpClient.CreateAsync(transport);

IList<McpClientTool> tools = await client.ListToolsAsync();

if (client.ServerCapabilities.Prompts is not null)
{
    var prompts = await client.ListPromptsAsync();
}

© managedcode, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 3 other files (references) in catalog/Libraries/MCP/skills/mcp of managedcode/dotnet-skills.

• SKILL.md
• manifest.json
• references/patterns.md
• references/security.md

Open the folder on GitHubat commit 535dd55