dotnet-mcp-builder
Build Model Context Protocol (MCP) servers in C#/.NET against the current ModelContextProtocol 2.x NuGet packages. Helps with cases the model gets wrong without guidance — stale versions (0.x preview or 1.x-era defaults), the v2 stateless-by-default HTTP flip, the 2026-07-28 spec deprecations (roots/sampling/logging), MCP Apps and Tasks extension packages, elicitation URL mode, per-session HTTP wiring, OAuth and reverse-proxy deploy specifics, and debugging MapMcp / STDIO / Streamable-HTTP errors. Also covers STDIO and Streamable HTTP transports (SSE is deprecated), tools, prompts, resources,
Profile →npx skills add github/awesome-copilot --skill dotnet-mcp-builder --agent copilot
Same command for any agent — swap --agent for claude-code, codex, cursor.
Weekly change comes from our own snapshots, not the repository page — it measures attention, not adoption.
# Building MCP servers in .NET This skill helps you write production-quality MCP servers and basic clients in C#/.NET against the **official** [`ModelContextProtocol`](https://www.nuget.org/profiles/ModelContextProtocol) NuGet packages, maintained by Microsoft and the MCP project. It targets the **stable 2.x** line and the current spec (2026-07-28). ## When this skill earns its keep The .NET MCP SDK had years of preview packages (`0.x-preview`) before reaching `1.0`, and v2 flipped several defaults. Without help, the model tends to: - Pin a stale preview version that won't compile against current samples. - Apply 1.x-era defaults that v2 reversed (HTTP was stateful by default; in 2.x `Stateless` defaults to `true`). - Recommend capabilities the 2026-07-28 spec deprecates (roots, sampling, MCP-channel logging — now `[Obsolete]`, warning `MCP9005`). - Miss recent spec features (multi-round-trip `input_required`, discovery-first negotiation, MCP Apps/Tasks extension packages, elicitation URL mode, structured content blocks). - Get HTTP transport details wrong (stateful/stateless, proxy buffering, OAuth wiring). - Forget the STDIO stdout/stderr trap. If the task is one of those, *load
- When this skill earns its keep
- Mental model in 30 seconds
- Decision tree → which references to load
- Cardinal rules (apply always; these prevent the highest-frequency breakages)
- Working style
- When the user is stuck
What does the dotnet-mcp-builder skill do?
Build Model Context Protocol (MCP) servers in C#/.NET against the current ModelContextProtocol 2.x NuGet packages. Helps with cases the model gets wrong without guidance — stale versions (0.x preview or 1.x-era defaults), the v2 stateless-by-default HTTP flip, the 2026-07-28 spec deprecations (roots/sampling/logging), MCP Apps and Tasks extension packages, elicitation URL mode, per-session HTTP wiring, OAuth and reverse-proxy deploy specifics, and debugging MapMcp / STDIO / Streamable-HTTP errors. Also covers STDIO and Streamable HTTP transports (SSE is deprecated), tools, prompts, resources,
How do I install it?
Run `npx skills add github/awesome-copilot --skill dotnet-mcp-builder --agent claude-code` — it drops the skill into your project so the agent can pick it up. Swap the --agent value for codex, cursor or copilot if you use one of those.
Where does this skill come from?
From github/awesome-copilot, a repository with 37,432 stars. We read it straight from the repository tree rather than a submitted listing, so what you see here is what is actually published.
Is a popular skill a good skill?
Not necessarily. Stars measure attention, not adoption — a repository can trend for a week and be abandoned. That is why we show the weekly change from our own snapshots next to the total, instead of a single flattering number.