Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add aboalrejal-ai/skills --skill dotnet-mcp-buildergit clone --depth 1 https://github.com/aboalrejal-ai/skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/aboalrejal-ai/skills/dotnet-mcp-builder)<a href="https://agentmods.dev/skills/aboalrejal-ai/skills/dotnet-mcp-builder"><img src="https://agentmods.dev/badge/skills/aboalrejal-ai/skills/dotnet-mcp-builder/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/aboalrejal-ai/skills/dotnet-mcp-builder"><img src="https://agentmods.dev/badge/skills/aboalrejal-ai/skills/dotnet-mcp-builder.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00233 | $0.01632 |
| Opus 5 | $0.00117 | $0.00816 |
| Sonnet 5 | $0.00047 | $0.00326 |
| Haiku 4.5 | $0.00023 | $0.00163 |
Grade A, and why
dotnet-mcp-builder scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
This is a copy
100% identical to dotnet-mcp-builder — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 84 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Building MCP servers in .NET
This skill helps you write production-quality MCP servers and basic clients in C#/.NET against the official ModelContextProtocol NuGet packages, maintained by Microsoft and the MCP project. It targets the stable 1.x line and the current spec (2025-11-25).
When this skill earns its keep
The .NET MCP SDK had years of preview packages (0.x-preview) before reaching 1.0. Without help, the model tends to:
- Pin a stale preview version that won't compile against current samples.
- Miss recent spec features (elicitation URL mode, MCP Apps, 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 the matching reference and follow it. If it's truly trivial (e.g. "rename this tool method"), you don't need to read everything — the cardinal rules below are the minimum.
Mental model in 30 seconds
A .NET MCP server is an ordinary Microsoft.Extensions.Hosting (or WebApplication) app that wires an MCP server through DI:
builder.Services
.AddMcpServer()
.WithStdioServerTransport() // OR .WithHttpTransport(...)
.WithToolsFromAssembly() // discover [McpServerToolType] classes
.WithPrompts<MyPrompts>() // optional
.WithResources<MyResources>(); // optional
Primitives are plain C# methods on classes marked with attributes ([McpServerToolType] + [McpServerTool], [McpServerPromptType] + [McpServerPrompt], [McpServerResourceType] + [McpServerResource]). Parameters bind from JSON-RPC; the SDK builds the JSON Schema from the signature plus [Description] attributes.
Server-to-client features (sampling, elicitation, roots, log/progress notifications) are methods on the injected IMcpServer.
Decision tree → which references to load
Always load references/packages.md if you're creating a new project or unsure of the current package version.
What ships with it
13 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
- references/client.md 5.8 KB
- references/elicitation.md 6.5 KB
- references/mcp-apps.md 8.9 KB
- references/packages.md 3.4 KB
- references/prompt-primitive.md 5.0 KB
- references/resource-primitive.md 6.1 KB
- references/roots.md 3.6 KB
- references/sampling.md 4.9 KB
- references/server-features.md 6.0 KB
- references/testing.md 5.9 KB
- references/tool-primitive.md 8.0 KB
- references/transport-http.md 6.8 KB
- references/transport-stdio.md 4.9 KB
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 8d ago First seen · 84 lines · 233 tokens per session scan A ce5efce47a11
dotnet-mcp-builder is a skill published in the GitHub repository aboalrejal-ai/skills (1 stars, last pushed 25d ago), licensed MIT. It adds 233 tokens to every session and 1,632 once invoked, about $0.0012 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to dotnet-mcp-builder, differing in 0 lines, and is treated as a copy.
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