mcp-server-dev

mcp-server-dev is a skill for Claude Code from andisab/swe-marketplace. It costs 175 tokens per session (1,512 once invoked), scanned A, original, MIT.

Instructions for building MCP servers: local programs that expose one or more tools for AI agents to call. It covers Python and TypeScript servers, communication over standard input and output, and packaging with uvx or npx.

In plain words
What is it for?
Use it to scaffold an MCP server, register tools, choose when a server is appropriate, and prepare it for distribution.
Why use it?
It helps turn related tools, shared connections, or domain-specific functions into a reusable service that other agent clients can start and call.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: mentions Claude Code.

Part of the context-engineering plugin — 7 skills, 1 agent shipped together

Good fit Use it to scaffold an MCP server, register tools, choose when a server is appropriate, and prepare it for distribution.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/andisab/swe-marketplace/mcp-server-dev
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 andisab/swe-marketplace --skill mcp-server-dev
Clone the repo
git clone --depth 1 https://github.com/andisab/swe-marketplace

Made for: Claude Code.

Or install context-engineering, the plugin that ships this one along with the rest of its 7 skills, 1 agent.

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 mcp-server-dev

README.md
[![agentmods](https://agentmods.dev/badge/skills/andisab/swe-marketplace/mcp-server-dev/github.svg)](https://agentmods.dev/skills/andisab/swe-marketplace/mcp-server-dev)
Your own site
<a href="https://agentmods.dev/skills/andisab/swe-marketplace/mcp-server-dev"><img src="https://agentmods.dev/badge/skills/andisab/swe-marketplace/mcp-server-dev/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.

agentmods 80×15 button for mcp-server-dev

Your own site · 80×15
<a href="https://agentmods.dev/skills/andisab/swe-marketplace/mcp-server-dev"><img src="https://agentmods.dev/badge/skills/andisab/swe-marketplace/mcp-server-dev.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 175 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,512 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. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 3 findings, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium MCP Rug Pull · line 6
    uvx/uv tool run commands without ==version create a rug-pull risk.
    Fix: Pin the version: uvx package-name==1.2.3
  • medium MCP Rug Pull · line 78
    uvx/uv tool run commands without ==version create a rug-pull risk.
    Fix: Pin the version: uvx package-name==1.2.3
  • medium MCP Rug Pull · line 93
    npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.
    Fix: Pin the version: npx @scope/[email protected]
How audits are shown
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 $0.00175 $0.01512
Opus 5 $0.00088 $0.00756
Sonnet 5 $0.00035 $0.00302
Haiku 4.5 $0.00017 $0.00151

Measured 9d ago against content hash f24267a8988e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

mcp-server-dev 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 9d 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.

plugins/context-engineering/skills/mcp-server-dev/SKILL.md · 161 lines

How it starts

The opening of the file, as written. The whole thing — 161 lines — stays where its author put it; the contents beside it link to each section on GitHub.

MCP Server Creation

Create multi-tool MCP servers in Python or TypeScript that follow the Model Context Protocol specification and Anthropic's tool design best practices.

What MCP Servers Are

An MCP server is a process that exposes one or more tools (and optionally resources and prompts) over the Model Context Protocol. Servers communicate via stdio transport — they read JSON-RPC from stdin and write responses to stdout.

MCP servers are how you package and distribute tool capabilities. An LLM client (Claude Code, Claude Desktop, etc.) starts the server process and calls its tools.

When to Create a Server

  • You have 2+ related tools that share configuration, state, or domain
  • You want to distribute tools for others to use (via uvx or npx)
  • Tools need shared resources (database connections, API clients, auth tokens)
  • You're building a domain-specific toolkit (GitHub, database, monitoring, etc.)

When NOT to Create a Server

  • Single utility tool — use a standalone tool file (see mcp-tool-dev skill)
  • Claude Code agent, skill, or command — use their respective creation skills
  • REST API — MCP is for LLM tool calling, not general HTTP services

Python vs TypeScript

Factor Python (FastMCP) TypeScript (@modelcontextprotocol/sdk)
Distribution uvx (uv tool) npx
Type system Type hints + docstrings Zod schemas
Packaging pyproject.toml package.json with bin
Async Native async/await Native async/await
Best for Data science, Python tooling, API wrappers Frontend tooling, Node.js ecosystem, npm distribution

Choose Python when the tools interact with Python libraries or you prefer pyproject.toml packaging. Choose TypeScript when targeting the npm ecosystem or when tools interact with Node.js libraries.

Creation Workflow

Step 1: Design Your Tools

List every tool with its name, description, parameters, and return format. Apply the consolidation principle: prefer fewer capable tools over many narrow ones.

Read the full file on GitHub · 161 lines

Files

What ships with it

3 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.

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. 9d ago First seen · 161 lines · 175 tokens per session scan A f24267a8988e

Subscribe to this mod's changes

mcp-server-dev is a skill published in the GitHub repository andisab/swe-marketplace (21 stars, last pushed 21d ago), licensed MIT. It adds 175 tokens to every session and 1,512 once invoked, about $0.0009 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.