create-mcp-server

create-mcp-server is a skill for Claude Code, Codex from open-gsd/gsd-pi. It costs 90 tokens per session (1,658 once invoked), scanned A, original, MIT.

A workflow for building an MCP server, a small service that gives an AI assistant tools for calling an external API or service.

In plain words
What is it for?
Use it to expose a service to an AI assistant, replace a custom integration, test the server, and evaluate whether its tools complete real tasks.
Why use it?
It helps turn raw API endpoints into focused tools with clear inputs, useful responses, and reliable error handling.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to expose a service to an AI assistant, replace a…

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Install with agentmods
npx agentmods add skills/open-gsd/gsd-pi/create-mcp-server
About the project

GSD Pi is a command-line coding agent and project workflow system that plans, implements, verifies, and tracks software work through milestones, tasks, Git worktrees, and stored project notes. It is for developers who want structured, longer-running agent sessions using different model providers. The catalogue entries extend GSD Pi with skills and agents.

open-gsd/gsd-pi · 1,201 stars · on GitHub · opengsd.net

Install

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.

Any agent
npx skills add open-gsd/gsd-pi --skill create-mcp-server
Clone the repo
git clone --depth 1 https://github.com/open-gsd/gsd-pi

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for create-mcp-server

README.md
[![agentmods](https://agentmods.dev/badge/skills/open-gsd/gsd-pi/create-mcp-server.svg)](https://agentmods.dev/skills/open-gsd/gsd-pi/create-mcp-server)
Your own site
<a href="https://agentmods.dev/skills/open-gsd/gsd-pi/create-mcp-server"><img src="https://agentmods.dev/badge/skills/open-gsd/gsd-pi/create-mcp-server.svg" alt="Measured on agentmods" height="20"></a>
Per session 90 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,658 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00090 $0.01658
Opus 5 $0.00045 $0.00829
Sonnet 5 $0.00018 $0.00332
Haiku 4.5 $0.00009 $0.00166

Measured 7d ago against content hash cc29de5c9c8e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

create-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 7d 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.

src/resources/skills/create-mcp-server/SKILL.md · 122 lines

How it starts

The opening of the file, as written. The whole thing — 122 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Invocation points:

  • User describes a service or API they want an LLM to reach
  • /gsd mcp init scaffolds config but there's a tool integration to build
  • Replacing a hand-rolled extension with a standard MCP server

<core_principle> THE QUALITY METRIC IS TASK COMPLETION, NOT SCHEMA VALIDITY. A server that lists 30 tools with cryptic names and empty descriptions passes the protocol but fails the point. The tool description is the only thing an LLM has to decide whether to call it — write it like documentation for a stranger under time pressure.

DESIGN FOR THE MODEL, NOT THE API. A raw REST endpoint is rarely the right tool. Group, filter, and pre-shape responses so the model gets what it needs to reason, not a 40KB JSON blob it has to summarize. Fewer, deeper tools beat many, shallow ones. </core_principle>

Step 1: Research and scope

  1. Study modern MCP design. Read the latest MCP protocol docs (not training data — fetch them). Read 2–3 reference implementations to see current patterns.
  2. Pick a framework. TypeScript is the default — the reference SDK is the most mature. Python is fine for data-heavy or ML adjacencies.
  3. Analyze the target API. Map the external service's endpoints, auth, rate limits, pagination, error shapes. Identify what a human workflow on top of it actually looks like — that's the cut line for tool design.
  4. Produce a brief. One page: what the server does, who calls it, the 5–10 tools you plan to expose, and the top 3 design trade-offs. Confirm with the user.

Read the full file on GitHub · 122 lines

Changes

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.

  1. 7d ago First seen · 122 lines · 90 tokens per session scan A cc29de5c9c8e

Subscribe to this mod's changes

create-mcp-server is a skill published in the GitHub repository open-gsd/gsd-pi (1,201 stars, last pushed today), licensed MIT. It adds 90 tokens to every session and 1,658 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.