mcp-builder

mcp-builder is a skill for Claude Code from ashrafmusa/agenticana. It costs 24 tokens per session (772 once invoked), scanned A, a copy of mcp-builder, MIT.

A guide to building MCP servers, which connect AI systems to external tools and data. It covers callable tools, readable resources, prompt templates, server structure, connection methods, input validation, and predictable output.

In plain words
What is it for?
Use it to plan or implement an MCP server, define tool schemas, organize resources and prompts, and choose between Stdio, SSE, and WebSocket transports.
Why use it?
It helps you design integrations that are understandable and safer for an AI agent to call. It also clarifies how local command-line connections differ from web and real-time connections.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Good fit Use it to plan or implement an MCP server, define tool schemas, organize resources and prompts, and choose between Stdio, SSE, and WebSocket transports.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/ashrafmusa/agenticana/mcp-builder
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 ashrafmusa/agenticana --skill mcp-builder
Clone the repo
git clone --depth 1 https://github.com/ashrafmusa/agenticana

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.

agentmods badge for mcp-builder

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

agentmods 80×15 button for mcp-builder

Your own site · 80×15
<a href="https://agentmods.dev/skills/ashrafmusa/agenticana/mcp-builder"><img src="https://agentmods.dev/badge/skills/ashrafmusa/agenticana/mcp-builder.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 24 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 772 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 100% copy Near-identical to another mod 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 $0.00024 $0.00772
Opus 5 $0.00012 $0.00386
Sonnet 5 $0.00005 $0.00154
Haiku 4.5 $0.00002 $0.00077

Measured 8d ago against content hash d13eb1291ed7, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, 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 8d 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.

Origin

This is a copy

100% identical to mcp-builder — 0 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.

skills/mcp-builder/SKILL.md · 177 lines

How it starts

The opening of the file, as written. The whole thing — 177 lines — stays where its author put it; the contents beside it link to each section on GitHub.

MCP Builder

Principles for building MCP servers.


1. MCP Overview

What is MCP?

Model Context Protocol - standard for connecting AI systems with external tools and data sources.

Core Concepts

Concept Purpose
Tools Functions AI can call
Resources Data AI can read
Prompts Pre-defined prompt templates

2. Server Architecture

Project Structure

my-mcp-server/
├── src/
│   └── index.ts      # Main entry
├── package.json
└── tsconfig.json

Transport Types

Type Use
Stdio Local, CLI-based
SSE Web-based, streaming
WebSocket Real-time, bidirectional

3. Tool Design Principles

Good Tool Design

Principle Description
Clear name Action-oriented (get_weather, create_user)
Single purpose One thing well
Validated input Schema with types and descriptions
Structured output Predictable response format

Input Schema Design

Field Required?
Type Yes - object
Properties Define each param
Required List mandatory params
Description Human-readable

4. Resource Patterns

Resource Types

Type Use
Static Fixed data (config, docs)
Dynamic Generated on request
Template URI with parameters

URI Patterns

Pattern Example
Fixed docs://readme
Parameterized users://{userId}
Collection files://project/*

5. Error Handling

Error Types

Situation Response
Invalid params Validation error message
Not found Clear "not found"
Server error Generic error, log details

Best Practices

  • Return structured errors
  • Don't expose internal details
  • Log for debugging
  • Provide actionable messages

6. Multimodal Handling

Supported Types

Type Encoding
Text Plain text
Images Base64 + MIME type
Files Base64 + MIME type

Read the full file on GitHub · 177 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. 8d ago First seen · 177 lines · 24 tokens per session scan A d13eb1291ed7

Subscribe to this mod's changes

mcp-builder is a skill published in the GitHub repository ashrafmusa/agenticana (2 stars, last pushed yesterday), licensed MIT. It adds 24 tokens to every session and 772 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to mcp-builder, differing in 0 lines, and is treated as a copy.

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