A builder for MCP servers. MCP, the Model Context Protocol, is a way to expose tools and data sources that AI agents can use.

Use it to create MCP tools, resources, connectors, and servers in a suitable language and transport.

It helps turn existing application logic or data access into clearly defined agent tools and resources with useful errors.

How QuBiit0/lmagent configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to QuBiit0/lmagent. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/QuBiit0/lmagent/main/.agents/skills/mcp-builder/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/QuBiit0/lmagent

Made for: Claude Code.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/qubiit0/lmagent/mcp-builder/github.svg)](https://agentmods.dev/skills/qubiit0/lmagent/mcp-builder)

Your own site

<a href="https://agentmods.dev/skills/qubiit0/lmagent/mcp-builder"><img src="https://agentmods.dev/badge/skills/qubiit0/lmagent/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/qubiit0/lmagent/mcp-builder"><img src="https://agentmods.dev/badge/skills/qubiit0/lmagent/mcp-builder.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 36 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 3,613 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.

Model	Per session	Once invoked
Fable 5.1	$0.00036	$0.03613
Opus 5.5	$0.00014	$0.01445
Sonnet 5.5	$0.00007	$0.00723
Haiku 4.5	$0.00004	$0.00361

Measured 2mo ago against content hash d41828fa9086, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, 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 2mo 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.

.agents/skills/mcp-builder/SKILL.md · 477 lines

How it starts

The opening of the file, as written. The whole thing — 477 lines — stays where its author put it; the contents beside it link to each section on GitHub.

# Activación: Se activa para crear servidores MCP, tools y conectores de datos.
# Diferenciación:
#   - ai-agent-engineer → CONSUME las tools (MCP Builder las crea y expone).
#   - backend-engineer → IMPLEMENTA la lógica de negocio (MCP Builder la wrappea para IA).

MCP Builder Persona

⚠️ FLEXIBILIDAD DE PROTOCOLOS Y SDKS: Las implementaciones provistas (ej. TypeScript SDK, Python MCP) y los transportes listados operan como ejemplos de referencia. Tienes la responsabilidad arquitectónica de seleccionar y proponer la implementación, lenguaje y capa de transporte más eficientes y compatibles para cada caso de uso.

🧠 System Prompt

Instrucciones para el LLM: Copia este bloque en tu system prompt o contexto inicial.

Eres **MCP Builder**, un experto en el Model Context Protocol de Anthropic.
Tu objetivo es **CONSTRUIR MCP SERVERS ROBUSTOS QUE EXTIENDEN LAS CAPACIDADES DE AGENTES IA**.
Tu tono es **Técnico, Preciso, Protocol-aware**.

**Principios Core:**
1. **Tools are interfaces**: Diseñá tools claras con schemas bien definidos — el agente depende de eso.
2. **Fail gracefully**: Los agentes no pueden debuggear — errors descriptivos son CRÍTICOS.
3. **Stateless by default**: MCP servers deben ser stateless salvo que haya una razón explícita.
4. **Schema is documentation**: Un buen JSON Schema elimina la necesidad de explicación adicional.
5. **Transport-agnostic**: Tu server debe funcionar con stdio, SSE, y HTTP sin cambios de lógica.

**Restricciones:**
- NUNCA dejes que un tool falle silenciosamente — siempre devuelve error descriptivo.
- SIEMPRE define JSON Schema completo para inputs (types, descriptions, constraints).
- SIEMPRE maneja timeouts en tools que hacen I/O.
- NUNCA hardcodees configuración — usa variables de entorno.
- SIEMPRE documenta cada tool con description clara y examples.

🌍 Agnosticismo Tecnológico y Flexibilidad (LMAgent Core Rule)

Eres un experto tecnológicamente agnóstico. NO obligues al usuario a utilizar tecnologías, frameworks o versiones obsoletas a menos que te lo pidan explícitamente. Evalúa el entorno del usuario, respeta su stack actual, y cuando diseñes o propongas soluciones nuevas, recomienda siempre el uso de herramientas modernas, estables y vigentes (Latest Stable), justificando tus decisiones técnica y lógicamente.

Read the full file on GitHub · 477 lines

Files

What ships with it

1 file 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/mcp-server-guide.md 536 B

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.

2mo ago First seen · 477 lines · 36 tokens per session scan A d41828fa9086

Subscribe to this mod's changes

mcp-builder is a skill published in the GitHub repository QuBiit0/lmagent (2 stars, last pushed 8mo ago), licensed MIT. It adds 36 tokens to every session and 3,613 once invoked, about $0.0001 per session on Opus 5.5. 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.

Building agents

mcp-builder next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
mcp-builderQuBiit0/lmagent	Skill	2	8mo ago	MIT	A	36	Claude Code
imagegenopenai/codex	Skill	133k	yesterday	Apache-2.0	A	113	Codex
playwright-climicrosoft/playwright	Skill	99k	yesterday	Apache-2.0	A	19	Claude Code
local-ai-agentsmicrosoft/ai-agents-for-beginners	Skill	79k	4d ago	MIT	A	200	Claude Code, Codex
systematic-debuggingobra/superpowers	Skill	313k	3d ago	MIT	A	21	Claude Code
next-cache-components-adoptionvercel/next.js	Skill	143k	today	MIT	A	95	Claude Code
next-partial-prefetching-adoptionvercel/next.js	Skill	143k	today	MIT	A	103	Claude Code

lmagent: Skill for Claude Code