build-tools

name	build-tools
description	Build MCP tool collections from discovered API groups. Reads .discover.json and generates tools and collection registrations. Use after running 'npx @umbraco-cms/create-umbraco-mcp-server discover'.
user_invocable	true

Build Tools

Generate MCP tool collections from the API groups selected during discovery. This skill reads .discover.json and the swagger spec, then builds tool files one collection at a time.

IMPORTANT: This skill ONLY creates tool files, collection indexes, and registrations. Do NOT create any test files, test setup, test builders, test helpers, or __tests__/ directories. Testing is handled separately by the /build-tools-tests skill.

Prerequisites

Before running, ensure:

1. You have run npx @umbraco-cms/create-umbraco-mcp-server discover (.discover.json exists)
2. The API client has been generated (src/umbraco-api/api/generated/ directory exists — if not, run npm run generate)

Arguments

• No arguments: build all collections from .discover.json
• Single collection name: build only that collection (e.g. /build-tools form)

Agents

This skill orchestrates the following agents — use them for the relevant steps:

Agent	When to use
mcp-tool-creator	Creating each tool file (Step 3b)
mcp-tool-description-writer	Writing tool descriptions (Step 3b)
mcp-tool-reviewer	Reviewing tools for LLM-readiness (Step 4)

Workflow

Process one collection at a time. Complete each collection fully before starting the next.

Step 0: Read Discovery Manifest

Read .discover.json from the project root:

{
  "apiName": "Umbraco Forms Management API",
  "swaggerUrl": "https://localhost:44324/umbraco/swagger/forms-management/swagger.json",
  "baseUrl": "https://localhost:44324",
  "collections": ["form", "form-template", "field-type", "folder"]
}

If an argument was provided, filter to only that collection. If .discover.json doesn't exist, tell the user to run npx @umbraco-cms/create-umbraco-mcp-server discover first.

Step 1: Check Generated Client

Check if src/umbraco-api/api/generated/ exists and contains .ts files. If not, run:

npm run generate

Then read the generated files to understand:

• The API client function name (e.g. getFormsManagementAPI)
• The available Zod schemas (in *.zod.ts files)
• The available client methods and their signatures

Step 2: Read Swagger Spec

Fetch the swagger spec from the swaggerUrl in .discover.json using curl:

curl -sk {swaggerUrl}

For each collection, find operations where tags[0] matches the collection's original tag name (the tag before kebab-case conversion). Collect:

• HTTP method
• Path
• operationId
• Summary
• Parameters and request body schema
• Response schema

Step 3: Per Collection — Create Tools

For each collection, skip if src/umbraco-api/tools/{collection}/index.ts already exists.

3a. Create directory structure

src/umbraco-api/tools/{collection}/
├── get/
├── post/
├── put/
└── delete/

Not every directory is needed — only create subdirectories for HTTP methods that have operations.

3b. Create tool files (one at a time, compile after each)

CRITICAL: Create ONE tool file, then immediately compile. Fix any errors before creating the next tool. This prevents errors from cascading across files.

Create one file per operation. Map operations to files:

HTTP Method	File pattern	Slice	Annotations
GET (single item by ID)	get/get-{entity}.ts	read	readOnlyHint: true
GET (list/collection)	get/list-{entities}.ts	list	readOnlyHint: true
GET (search)	get/search-{entities}.ts	search	readOnlyHint: true
POST	post/create-{entity}.ts	create	destructiveHint: false, idempotentHint: false
PUT/PATCH	put/update-{entity}.ts	update	idempotentHint: true
DELETE	delete/delete-{entity}.ts	delete	destructiveHint: true

Each tool file follows this pattern:

import {
  withStandardDecorators,
  executeGetApiCall,     // GET operations
  executeVoidApiCall,    // DELETE/PUT operations
  createToolResult,      // POST operations (manual handling)
  getApiClient,          // POST operations (manual handling)
  UmbracoApiError,       // POST operations (manual handling)
  CAPTURE_RAW_HTTP_RESPONSE,
  ToolDefinition,
} from "@umbraco-cms/mcp-server-sdk";
import type { getYourAPI } from "../../../api/generated/yourApi.js";
import { inputSchema, outputSchema } from "../../../api/generated/yourApi.zod.js";

type ApiClient = ReturnType<typeof getYourAPI>;

const tool: ToolDefinition<typeof inputSchema.shape, typeof outputSchema> = {
  name: "action-entity",
  description: "Clear description starting with action verb.",
  inputSchema: inputSchema.shape,
  outputSchema,
  slices: ["read"],
  annotations: { readOnlyHint: true },
  handler: async (params) => {
    return executeGetApiCall<ReturnType<ApiClient["method"]>, ApiClient>(
      (client) => client.method(params, CAPTURE_RAW_HTTP_RESPONSE)
    );
  },
};

export default withStandardDecorators(tool);

Key rules:

• Use Zod schemas from the generated *.zod.ts files for input/output
• For POST/create: use manual handling with getApiClient, extract ID from Location header
• For DELETE/PUT: use executeVoidApiCall
• For GET: use executeGetApiCall
• Never require UUIDs from the LLM — generate them server-side
• Keep input schemas to 3-5 fields max — hide complexity
• Write descriptions as mini-prompts: what it does, key constraints, when to use

After creating EACH tool file, run npm run compile. Fix any TypeScript errors in that file before creating the next one. Common issues:

• Wrong import path for the Zod schema (check the generated *.zod.ts file for the exact export name)
• Type mismatch between Zod shape and the API client method signature
• Missing CAPTURE_RAW_HTTP_RESPONSE parameter

3c. Create collection index.ts

import { ToolCollectionExport } from "@umbraco-cms/mcp-server-sdk";
import getTool from "./get/get-entity.js";
import listTool from "./get/list-entities.js";
// ... other imports

const collection: ToolCollectionExport = {
  metadata: {
    name: "{collection-name}",
    displayName: "{Display Name} Tools",
    description: "Tools for managing {entity} resources",
  },
  tools: () => [getTool, listTool, /* ... */],
};

export default collection;

3d. Register collection

Add the collection import and registration to src/index.ts:

1. Add an import at the top with the other collection imports:

   import {collection}Collection from "./tools/{collection}/index.js";
   

2. Add it to the collections array:

   const collections = [existingCollection, {collection}Collection];
   

3. If configureApiClient still references the example/template API client, update it to use the correct generated client getter (e.g. getUmbracoEngageManagementAPI). Check the import from ./umbraco-api/api/generated/ and ensure it matches.

4. Do the same for src/collections.ts — add the collection import and add it to the exported array.

3e. Compile

npm run compile

Fix any TypeScript errors before proceeding. Common issues:

• Wrong import paths to generated client
• Mismatched Zod schema shapes
• Missing CAPTURE_RAW_HTTP_RESPONSE parameter

Step 4: Per Collection — Review with mcp-tool-reviewer

After all tools are created for a collection, run the mcp-tool-reviewer agent on the collection. The agent will check each tool against the LLM-readiness checklist:

• Schema simplification (max 3-5 fields, no nested objects, no UUID generation from LLM)
• Description quality (action verbs, constraints, when NOT to use)
• Response shaping (essential fields only, actionable errors)
• Composite tool opportunities (flag sequences that should be bundled)
• Naming & annotations (consistent, correct hints per HTTP method)
• Context & scope (no redundant tools, reasonable count)
• Pagination design (appropriate page sizes, documented mechanics)

Flag any issues but continue to the next collection. The user can address review findings afterwards.

Step 5: Next Collection

Repeat steps 3-4 for the next collection in .discover.json.

Step 6: Final Verification

After all collections are built:

npm run compile    # Full type check

Then run /count-mcp-tools to confirm all collections are covered. All collections from .discover.json should show tool count > 0. If any show "Not started", report which collections were missed.

Report what was generated:

• Number of collections created
• Number of tools per collection
• Any review issues found
• Any collections skipped (already existed)

Next step: Run /build-tools-tests to generate integration tests for the tool collections.