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 pproenca/dot-skills --skill build-mcp-servergit clone --depth 1 https://github.com/pproenca/dot-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/pproenca/dot-skills/build-mcp-server)<a href="https://agentmods.dev/skills/pproenca/dot-skills/build-mcp-server"><img src="https://agentmods.dev/badge/skills/pproenca/dot-skills/build-mcp-server/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/pproenca/dot-skills/build-mcp-server"><img src="https://agentmods.dev/badge/skills/pproenca/dot-skills/build-mcp-server.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 | $0.00104 | $0.02882 |
| Opus 5 | $0.00052 | $0.01441 |
| Sonnet 5 | $0.00021 | $0.00576 |
| Haiku 4.5 | $0.00010 | $0.00288 |
Grade A, and why
build-mcp-server 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 5d 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
81% identical to build-mcp-server — 71 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 — 243 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Build an MCP Server
You are guiding a developer through designing and building an MCP server that works seamlessly with Claude. MCP servers come in many forms — picking the wrong shape early causes painful rewrites later. Your first job is discovery, not code.
Do not start scaffolding until you have answers to the questions in Phase 1. If the user's opening message already answers them, acknowledge that and skip straight to the recommendation.
When to Apply
- User asks to build, create, or scaffold an MCP server
- User wants to wrap a REST/GraphQL API for use with Claude
- User wants to expose tools, resources, or prompts via MCP
- User is choosing between deployment models (remote HTTP, MCPB, local stdio)
- User is designing tool schemas for an MCP integration
Workflow Overview
Phase 1: Discovery → Phase 2: Deployment model → Phase 3: Tool pattern → Phase 4: Framework → Phase 5: Scaffold
Each phase narrows the design space. After Phase 5, hand off to the appropriate scaffold reference or companion skill.
Prerequisites
- TypeScript path: Node.js >= 18, npm
- Python path: Python >= 3.10, pip
- Testing:
npx(ships with npm) — used byscripts/test-server.shand the MCP Inspector
Phase 1 — Interrogate the use case
Ask these questions conversationally (batch them into one message, don't interrogate one-at-a-time). Adapt wording to what the user has already told you.
1. What does it connect to?
| If it connects to… | Likely direction |
|---|---|
| A cloud API (SaaS, REST, GraphQL) | Remote HTTP server |
| A local process, filesystem, or desktop app | MCPB or local stdio |
| Hardware, OS-level APIs, or user-specific state | MCPB |
| Nothing external — pure logic / computation | Either — default to remote |
2. Who will use it?
- Just me / my team, on our machines → Local stdio is acceptable (easiest to prototype)
- Anyone who installs it → Remote HTTP (strongly preferred) or MCPB (if it must be local)
- Users of Claude desktop who want UI widgets → MCP app (remote or MCPB)
What ships with it
11 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.
- gotchas.md 82 B
- metadata.json 704 B
- references/auth.md 4.7 KB
- references/deploy-cloudflare-workers.md 3.8 KB
- references/elicitation.md 4.6 KB
- references/remote-http-scaffold.md 6.9 KB
- references/resources-and-prompts.md 4.0 KB
- references/server-capabilities.md 4.6 KB
- references/tool-design.md 6.0 KB
- references/versions.md 668 B
- scripts/test-server.sh 1.2 KB runs code
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.
- 5d ago First seen · 243 lines · 104 tokens per session scan A 7cc963d0c3a0
build-mcp-server is a skill published in the GitHub repository pproenca/dot-skills (205 stars, last pushed 24d ago), licensed MIT. It adds 104 tokens to every session and 2,882 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. It is 81% identical to build-mcp-server, differing in 71 lines, and is treated as a copy.
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