studio: Skill for Claude Code

.claude/skills/add-mcp-tools/SKILL.md

add-mcp-tools is a skill for Claude Code from decocms/studio. It costs 27 tokens per session (2,268 once invoked), scanned A, original, MIT.

A guide for adding new Model Context Protocol tools to the Studio codebase, including their input rules, access checks, authentication, and file layout.

In plain words
What is it for?
Building tools that create, list, update, or delete resources such as API keys, webhooks, or secrets.
Why use it?
It provides the repeated structure needed for new tools to behave consistently and safely within the application.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is decocms/studio's own configuration. It tells Claude Code how to work on studio 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 studio configures →

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is import { defineTool } from "../../core/define-tool";.

Reuse

Borrowing it

Nothing to install: this file belongs to decocms/studio. 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/decocms/studio/main/.claude/skills/add-mcp-tools/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/decocms/studio

Made for: Claude Code.

Wrote this? Show the measurements

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Per session 27 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,268 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 $0.00027 $0.02268
Opus 5.5 $0.00011 $0.00907
Sonnet 5.5 $0.00005 $0.00454
Haiku 4.5 $0.00003 $0.00227

Measured 2mo ago against content hash 07afc9e9fc59, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

add-mcp-tools 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.

.claude/skills/add-mcp-tools/SKILL.md · 372 lines

How it starts

The opening of the file, as written. The whole thing — 372 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Adding New MCP Tools to Studio

This guide documents the pattern for adding new MCP tools to Studio codebase. Follow this checklist to ensure consistency with existing tools.

Overview

MCP tools are exposed via the Model Context Protocol and allow programmatic management of resources. Each tool follows a consistent pattern with:

  • Zod schemas for input/output validation
  • defineTool for automatic tracing, metrics, and audit logging
  • Access control via ctx.access.check()
  • Better Auth integration via ctx.boundAuth

File Structure

When adding a new domain of tools (e.g., apiKeys, webhooks, secrets), create the following structure:

apps/api/src/tools/<domain>/
├── schema.ts     # Zod schemas for entities and operations
├── create.ts     # <DOMAIN>_CREATE tool
├── list.ts       # <DOMAIN>_LIST tool
├── update.ts     # <DOMAIN>_UPDATE tool  
├── delete.ts     # <DOMAIN>_DELETE tool
└── index.ts      # Barrel export

Step-by-Step Checklist

1. Create Schema File (schema.ts)

Define Zod schemas for:

  • Entity schema: The resource returned in list/get operations
  • Create input/output schemas: Input for creation, output includes created entity
  • Update input/output schemas: Partial updates
  • Delete input/output schemas: ID input, success confirmation output
// apps/api/src/tools/<domain>/schema.ts
import { z } from "zod";

// Entity schema (what's returned in list operations)
export const MyEntitySchema = z.object({
  id: z.string(),
  name: z.string(),
  // ... other fields
  createdAt: z.union([z.string(), z.date()]),
});

export type MyEntity = z.infer<typeof MyEntitySchema>;

// Create schemas
export const MyCreateInputSchema = z.object({
  name: z.string().min(1).max(255),
  // ... other fields
});

export const MyCreateOutputSchema = z.object({
  item: MyEntitySchema,
});

// List schemas
export const MyListInputSchema = z.object({
  // pagination, filters, etc.
});

export const MyListOutputSchema = z.object({
  items: z.array(MyEntitySchema),
});

// Update schemas
export const MyUpdateInputSchema = z.object({
  id: z.string(),
  // ... partial fields
});

export const MyUpdateOutputSchema = z.object({
  item: MyEntitySchema,
});

// Delete schemas
export const MyDeleteInputSchema = z.object({
  id: z.string(),
});

export const MyDeleteOutputSchema = z.object({
  success: z.boolean(),
  id: z.string(),
});

Read the full file on GitHub · 372 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. 2mo ago First seen · 372 lines · 27 tokens per session scan A 07afc9e9fc59

Subscribe to this mod's changes

add-mcp-tools is a skill published in the GitHub repository decocms/studio (415 stars, last pushed yesterday), licensed MIT. It adds 27 tokens to every session and 2,268 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 2026-08-30.

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