A guide for building MCP servers, which let language models use carefully designed tools to interact with outside services. It covers Python with FastMCP and Node or TypeScript with the MCP SDK.

For creating MCP servers that integrate external APIs or services, using Python, Node, or TypeScript.

It helps avoid guessing how to design a server that connects an AI assistant to an API or other service. It focuses on making the tools clear and reliable.

How CyperNexus/blockbench-mcp configures Claude Code and Codex

Reuse

Borrowing it

Nothing to install: this file belongs to CyperNexus/blockbench-mcp. 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/CyperNexus/blockbench-mcp/main/.agents/skills/mcp-builder/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/CyperNexus/blockbench-mcp

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.

README.md

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

Your own site

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

Per session 61 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,938 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 unknown 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	$0.00061	$0.01938
Opus 5.5	$0.00024	$0.00775
Sonnet 5.5	$0.00012	$0.00388
Haiku 4.5	$0.00006	$0.00194

Measured 2mo ago against content hash 0f4592dcb53c, 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.

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.

.agents/skills/mcp-builder/SKILL.md · 237 lines

The source is not reproduced here

Licensed GPL-3.0

The repository is licensed GPL-3.0, which this catalogue does not treat as permission to reproduce the file. Read it at the source.

Read it on GitHub

Files

What ships with it

9 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.

2mo ago First seen · 237 lines · 61 tokens per session scan A 0f4592dcb53c

Subscribe to this mod's changes

mcp-builder is a skill published in the GitHub repository CyperNexus/blockbench-mcp (0 stars, last pushed 4mo ago), licensed GPL-3.0. It adds 61 tokens to every session and 1,938 once invoked, about $0.0002 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-builderCyperNexus/blockbench-mcp	Skill	0	4mo ago	GPL-3.0	A	61	Claude Code, Codex
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

blockbench-mcp: Skill for Claude Code