MCP Builder

MCP Builder is a skill for Claude Code, Codex from Poorgramer-Zack/copilot-cli-things. It costs 57 tokens per session (1,929 once invoked), scanned A, original, MIT.

A guide for building and testing MCP servers in TypeScript or Python. MCP, or Model Context Protocol, lets an AI agent use tools that connect to outside services.

In plain words
What is it for?
Use it to design tool interfaces, add input validation, choose local or web connections, and create tests and setup documentation for an MCP server.
Why use it?
It helps turn an outside service into clearly defined tools an agent can discover and use, with validated inputs, outputs, and useful errors.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/poorgramer-zack/copilot-cli-things/mcp-builder
Any agent
npx skills add Poorgramer-Zack/copilot-cli-things --skill mcp-builder
Clone the repo
git clone --depth 1 https://github.com/Poorgramer-Zack/copilot-cli-things

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 MCP Builder

README.md
[![agentmods](https://agentmods.dev/badge/skills/poorgramer-zack/copilot-cli-things/mcp-builder.svg)](https://agentmods.dev/skills/poorgramer-zack/copilot-cli-things/mcp-builder)
Your own site
<a href="https://agentmods.dev/skills/poorgramer-zack/copilot-cli-things/mcp-builder"><img src="https://agentmods.dev/badge/skills/poorgramer-zack/copilot-cli-things/mcp-builder.svg" alt="Measured on agentmods" height="20"></a>
Per session 57 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,929 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00057 $0.01929
Opus 5 $0.00028 $0.00964
Sonnet 5 $0.00011 $0.00386
Haiku 4.5 $0.00006 $0.00193

Measured 4d ago against content hash 7806462366b7, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

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 4d ago.

The scan reads SKILL.md. This mod also ships 2 executable files (scripts/connections.py, scripts/evaluation.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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/mcp-builder/skills/mcp-builder/SKILL.md · 232 lines

How it starts

The opening of the file, as written. The whole thing — 232 lines — stays where its author put it; the contents beside it link to each section on GitHub.

MCP Server Development Guide

Build MCP (Model Context Protocol) servers that enable LLMs to interact with external services through well-designed tools.

Deliverables: working MCP server with well-designed tools, clear tool descriptions/input schemas/annotations, evaluation suite, and setup documentation.


Phase 1: Deep Research and Planning

1.1 Understand Modern MCP Design

API Coverage vs. Workflow Tools: Balance comprehensive API endpoint coverage with specialized workflow tools. When uncertain, prioritize comprehensive API coverage — it gives agents flexibility to compose operations.

Tool Naming and Discoverability:

  • Use snake_case with service prefix: {service}_{action}_{resource}
  • Examples: slack_send_message, github_create_issue
  • Be action-oriented: start with verbs (get, list, search, create, update, delete)

Context Management: Design tools that return focused, relevant data. Support pagination and filtering to avoid overwhelming responses.

Actionable Error Messages: Error messages should guide agents toward solutions with specific suggestions and next steps.

1.2 Study MCP Protocol

Start with the sitemap: https://modelcontextprotocol.io/sitemap.xml Fetch specific pages with .md suffix (e.g., https://modelcontextprotocol.io/specification/draft.md).

Key pages: specification overview, transport mechanisms (streamable HTTP, stdio), tool/resource/prompt definitions.

1.3 Choose Framework

Recommended stack:

  • Language: TypeScript (strong SDK support, good AI code generation, static typing)
  • Transport: Streamable HTTP for remote servers (stateless JSON), stdio for local servers

Framework documentation:

Read the full file on GitHub · 232 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. 4d ago First seen · 232 lines · 57 tokens per session scan A 7806462366b7

Subscribe to this mod's changes

MCP Builder is a skill published in the GitHub repository Poorgramer-Zack/copilot-cli-things (2 stars, last pushed 5mo ago), licensed MIT. It adds 57 tokens to every session and 1,929 once invoked, about $0.0003 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 2026-08-31.

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