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mcpfusion: Skill for Claude Code

.claude/skills/mcpfusion-development/SKILL.md

mcpfusion-development is a skill for Claude Code from vinkius-labs/mcpfusion. It costs 119 tokens per session (4,373 once invoked), scanned A, original, Apache-2.0.

A guide to building MCP servers in TypeScript with MCP Fusion, a framework for connecting AI assistants to tools and data. It explains how to structure data validation, responses, tools, prompts, middleware, routing, configuration, and tests.

In plain words
What is it for?
Use it when creating, changing, or reviewing MCP Fusion servers, including tools, data models, presenters, routers, middleware, prompts, tests, or setup.
Why use it?
It gives developers a consistent way to organize MCP Fusion code and choose between its server patterns. It also provides runnable examples for common server tasks.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is vinkius-labs/mcpfusion's own configuration. It tells Claude Code how to work on mcpfusion itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything mcpfusion configures →

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is For the complete API reference with all type signatures, read [llms.txt](../../../llms.txt) at the root of the repository. This skill covers the essential patte.

not rated 255repo 1mo ago A scan SkillSpector: pass 119 tokens original Apache-2.0
View source ↗ vinkius-labs/mcpfusion vinkius.com
Reuse

Borrowing it

Nothing to install: this file belongs to vinkius-labs/mcpfusion. 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/vinkius-labs/mcpfusion/main/.claude/skills/mcpfusion-development/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/vinkius-labs/mcpfusion

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 mcpfusion-development

README.md
[![agentmods](https://agentmods.dev/badge/skills/vinkius-labs/mcpfusion/mcpfusion-development/github.svg)](https://agentmods.dev/skills/vinkius-labs/mcpfusion/mcpfusion-development)
Your own site
<a href="https://agentmods.dev/skills/vinkius-labs/mcpfusion/mcpfusion-development"><img src="https://agentmods.dev/badge/skills/vinkius-labs/mcpfusion/mcpfusion-development/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 mcpfusion-development

Your own site · 80×15
<a href="https://agentmods.dev/skills/vinkius-labs/mcpfusion/mcpfusion-development"><img src="https://agentmods.dev/badge/skills/vinkius-labs/mcpfusion/mcpfusion-development.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 119 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,373 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 pass 7 Sept 2026
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 $0.00119 $0.04373
Opus 5.5 $0.00048 $0.01749
Sonnet 5.5 $0.00024 $0.00875
Haiku 4.5 $0.00012 $0.00437

Measured 2mo ago against content hash 699746ef0438, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

mcpfusion-development 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 4 executable files (references/example-complete-crud.ts, references/example-proxy-api.ts, references/example-server-setup.ts, …), 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.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

.claude/skills/mcpfusion-development/SKILL.md · 488 lines

How it starts

The opening of the file, as written. The whole thing — 488 lines — stays where its author put it; the contents beside it link to each section on GitHub.

mcpfusion development Guide

MCP Fusion is a TypeScript framework for MCP servers built on the MVA (Model-View-Agent) pattern. The Model validates data, the Presenter (View) shapes what the AI perceives, and Tools (Agent layer) wire it all together.

For the complete API reference with all type signatures, read llms.txt at the root of the repository. This skill covers the essential patterns and rules.

Reference Examples

Complete, runnable examples are available in references/. Read them for concrete implementation patterns:

Example Domain Patterns Shown
example-complete-crud.ts Product Catalog Full MVA lifecycle: Model → Presenter → Router → Query/Mutation/Action, ErrorBuilder, State Sync
example-proxy-api.ts Blog Platform .proxy() API pass-through, .fromModel(), field aliases, path params (:id), .handle() vs .proxy() decision tree
example-server-setup.ts Generic App Full server bootstrap: context, initMCPFusion(), middleware, autoDiscover(), prompts, State Sync policies, startServer()
example-testing.ts Customer Service @mcpfusion/testing: Egress Firewall assertions, JIT System Rules, RBAC middleware, error handling, Symbol Invisibility

Project Structure

src/
├── models/               ← M — defineModel() declarations
│   ├── InvoiceModel.ts
│   └── UserModel.ts
├── views/                ← V — Presenters
│   ├── invoice.presenter.ts
│   └── user.presenter.ts
├── agents/               ← A — Tool definitions
│   ├── billing.tool.ts
│   └── users.tool.ts
├── index.ts              ← ToolRegistry + registerAll()
└── server.ts             ← attachToServer() bootstrap

Layer import rule: agents/ → views/ → models/ → @mcpfusion/core. Never import backwards.

The Golden Rules

  1. ALWAYS use defineModel() for domain entity schemas — never raw z.object(). Models go in models/.
  2. Presenters receive Models via .schema(MyModel) — the Presenter is the egress firewall.
  3. with*() methods are for tool INPUT parameters only (filters, IDs, pagination) — NOT for domain schemas.
  4. Handlers return raw data — the framework wraps with success() automatically. No boilerplate.
  5. One Model + one Presenter per entity, reused across every tool and prompt.
  6. Use semantic verbs: f.query() = readOnly, f.mutation() = destructive, f.action() = neutral.

Read the full file on GitHub · 488 lines

Files

What ships with it

4 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. 2mo ago First seen · 488 lines · 119 tokens per session scan A 699746ef0438

Subscribe to this mod's changes

mcpfusion-development is a skill published in the GitHub repository vinkius-labs/mcpfusion (255 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 119 tokens to every session and 4,373 once invoked, about $0.0005 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 2026-08-30.

Backend and APIsBuilding agentschatgptclaudemcpmcp-frameworkmcp-servermodel-context-protocol
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