build-evals

name	build-evals
description	Build LLM eval tests for MCP tool collections. Reads .discover.json and creates eval setup and scenario test files per collection. Use after running '/build-tools'.
user_invocable	true

Build Evals

Generate LLM eval tests for MCP tool collections created by /build-tools. This skill reads .discover.json and the existing tool files, then builds eval test files in tests/evals/ one collection at a time.

IMPORTANT: This skill ONLY creates files inside tests/evals/ — the setup file and eval test files. Do NOT create or modify tool files, collection indexes, integration tests, mock handlers, or any other files.

Key difference from integration tests (/build-tools-tests):

• Integration tests: one file per tool, test handlers directly against real API, deterministic
• Eval tests: group related tools by workflow, test via Claude Agent SDK, probabilistic, require npm run build first (run against dist/)

Prerequisites

Before running, ensure:

1. You have run /build-tools (tool collections exist in src/umbraco-api/tools/)
2. The project builds: npm run build
3. An LLM API key is available (eval tests use Claude Agent SDK — works with a Claude Code subscription or ANTHROPIC_API_KEY)

Arguments

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

Agents

This skill orchestrates the following agent — use it for the relevant step:

Agent	When to use
eval-test-creator	Creating eval test files (Step 5)

Critical Rules

BUILD BEFORE RUNNING. Eval tests run against dist/index.js. Always npm run build first.

ONE COLLECTION AT A TIME. Complete each collection before starting the next.

GROUP TOOLS BY WORKFLOW. Unlike integration tests (one file per tool), eval tests group related tools into workflow scenarios. A collection with 5 tools might have just 1-2 eval test files.

ITERATE ON PROMPTS. Eval tests are probabilistic. If a test fails, the fix is usually in the prompt — make instructions more explicit, add search steps for IDs, use unique identifiers.

VERBOSE DURING DEVELOPMENT. Always set verbose: true when creating/debugging. Disable after tests pass reliably.

RUN COMMANDS SEPARATELY. Always run build and test as separate Bash calls. Never chain them with &&.

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 Prerequisites

For each collection, verify:

• src/umbraco-api/tools/{collection}/index.ts exists — if not, skip and tell the user to run /build-tools first

Check if eval tests already exist for this collection by looking for tests/evals/{collection}-*.test.ts files. Skip if eval test files already exist — evals have already been created for this collection.

Then ensure the eval setup exists and the project builds:

• If tests/evals/helpers/e2e-setup.ts doesn't exist, create it (Step 3)
• If tests/evals/jest.config.ts doesn't exist, create it (Step 3)

npm run build

Fix any build errors before continuing. Evals run against dist/index.js — if it doesn't build, evals can't run.

Step 2: Read Tool Files

For each collection, read:

• src/umbraco-api/tools/{collection}/index.ts — to get the list of tools and collection metadata
• Each tool file — to understand:
  • Tool names
  • Input schemas (what parameters each tool accepts)
  • Descriptions (what each tool does)
  • Slices (read, list, create, update, delete, search, etc.)

Build a mental inventory of which operations are available. This determines what workflow scenarios to create.

Step 3: Create Eval Setup (if not exists)

Eval tests use a centralized setup at tests/evals/. Only create these files if they don't already exist.

tests/evals/jest.config.ts

import type { Config } from "jest";

const config: Config = {
  preset: "ts-jest/presets/js-with-ts-esm",
  testEnvironment: "node",
  extensionsToTreatAsEsm: [".ts"],
  rootDir: "../..",
  moduleNameMapper: {
    "^(\\.{1,2}/.*)\\.js$": "$1",
    "^@/(.*)$": "<rootDir>/src/$1",
  },
  transform: {
    "^.+\\.tsx?$": [
      "ts-jest",
      {
        useESM: true,
      },
    ],
  },
  testMatch: ["<rootDir>/tests/evals/**/*.test.ts"],
  setupFilesAfterEnv: ["<rootDir>/tests/evals/helpers/e2e-setup.ts"],
  setupFiles: ["<rootDir>/jest.setup.ts"],
  testPathIgnorePatterns: ["/node_modules/"],
  moduleFileExtensions: ["ts", "tsx", "js", "jsx", "json", "node"],
  maxConcurrency: 1,
  maxWorkers: 1,
  testTimeout: 120000,
  slowTestThreshold: 300,
};

export default config;

tests/evals/helpers/e2e-setup.ts

Detect API mode: Check if src/mocks/ exists with handler files. If mocks exist, use USE_MOCK_API: "true". Otherwise, configure for real API using .env credentials.

Mock API setup (if src/mocks/ exists):

import path from "path";
import { configureEvals, ClaudeModels } from "@umbraco-cms/mcp-server-sdk/evals";

configureEvals({
  mcpServerPath: path.resolve(process.cwd(), "dist/index.js"),
  mcpServerName: "{mcp-server-name}",
  serverEnv: {
    USE_MOCK_API: "true",
    DISABLE_MCP_CHAINING: "true",
    UMBRACO_CLIENT_ID: "test-client",
    UMBRACO_CLIENT_SECRET: "test-secret",
    UMBRACO_BASE_URL: "http://localhost:9999",
  },
  defaultModel: ClaudeModels.Haiku,
  defaultMaxTurns: 10,
  defaultMaxBudgetUsd: 0.25,
  defaultTimeoutMs: 60000,
});

Real API setup (no mocks):

import path from "path";
import { configureEvals, ClaudeModels } from "@umbraco-cms/mcp-server-sdk/evals";

configureEvals({
  mcpServerPath: path.resolve(process.cwd(), "dist/index.js"),
  mcpServerName: "{mcp-server-name}",
  serverEnv: {
    UMBRACO_CLIENT_ID: process.env.UMBRACO_CLIENT_ID || "",
    UMBRACO_CLIENT_SECRET: process.env.UMBRACO_CLIENT_SECRET || "",
    UMBRACO_BASE_URL: process.env.UMBRACO_BASE_URL || "",
    DISABLE_MCP_CHAINING: "true",
  },
  defaultModel: ClaudeModels.Haiku,
  defaultMaxTurns: 10,
  defaultMaxBudgetUsd: 0.25,
  defaultTimeoutMs: 60000,
});

Key rules:

• Uses process.cwd() to resolve dist/index.js — setup runs from project root via Jest
• Get mcpServerName from package.json name field or src/index.ts
• Set DISABLE_MCP_CHAINING: "true" to avoid connecting to chained servers during tests
• Use conservative defaults: Haiku model, 10 turns, $0.25 budget, 60s timeout
• This file is loaded automatically via setupFilesAfterEnv — test files do NOT need to import it

Also ensure the test:evals script in package.json uses the dedicated config:

"test:evals": "npm run build && node --experimental-vm-modules $(npm root)/jest/bin/jest.js --config tests/evals/jest.config.ts --runInBand --forceExit"

Step 4: Design Eval Scenarios

Based on the tools available in the collection (from Step 2), design 1-2 workflow scenarios:

CRUD Lifecycle (if create + list/get + update + delete tools exist)

Test the full create-read-update-delete cycle:

1. Create an item with a unique name (use timestamp)
2. List items to confirm it was created
3. Get the specific item by ID
4. Update the item
5. Delete the item

Read-Only Workflow (if only get/list/search tools exist)

Test read operations:

1. List items
2. Get details for a specific item from the list

Search Workflow (if search + get tools exist)

Test search and retrieval:

1. Search for items matching a criteria
2. Get details for a result

Hierarchical Workflow (if folder/tree tools exist)

Test hierarchy operations:

1. Create a folder/container
2. Create an item inside the folder
3. List/navigate the hierarchy
4. Clean up

Aim for 1-2 scenarios per collection. A collection with CRUD tools needs one lifecycle test. A collection with only read tools needs one read-only test.

Step 5: Create Eval Test Files

Use the eval-test-creator agent.

Create one file per workflow scenario in tests/evals/: tests/evals/{collection}-{workflow}.test.ts

File naming

Workflow	File name
CRUD lifecycle	{collection}-crud.test.ts
Read-only	{collection}-read.test.ts
Search	{collection}-search.test.ts
Hierarchical	{collection}-hierarchy.test.ts

Test file pattern

import { describe, it } from "@jest/globals";
import {
  runScenarioTest,
  setupConsoleMock,
  getDefaultTimeoutMs,
} from "@umbraco-cms/mcp-server-sdk/evals";

const COLLECTION_TOOLS = [
  "create-entity",
  "list-entities",
  "get-entity",
  "update-entity",
  "delete-entity",
] as const;

describe("{Collection} CRUD Operations", () => {
  setupConsoleMock();
  const timeout = getDefaultTimeoutMs();

  it(
    "should complete full CRUD workflow",
    runScenarioTest({
      prompt: `Complete these tasks in order:
1. Generate a unique identifier using the current timestamp
2. Create a new entity named "Eval Test {timestamp}" with description "Created by eval test"
3. List all entities and confirm the one you created appears in the results
4. Get the entity you created by its ID to verify the details
5. Update the entity name to "Updated Eval Test {timestamp}"
6. Delete the entity you created
7. Say "CRUD workflow completed successfully"`,
      tools: [...COLLECTION_TOOLS],
      requiredTools: ["create-entity", "list-entities", "get-entity", "update-entity", "delete-entity"],
      successPattern: "CRUD workflow completed successfully",
      verbose: true,
    }),
    timeout
  );
});

Note: No setup import needed — e2e-setup.ts is loaded automatically via setupFilesAfterEnv in tests/evals/jest.config.ts.

Prompt writing rules

• Numbered steps — clear, sequential instructions
• Unique identifiers — use timestamps to avoid collisions between test runs
• Search for IDs dynamically — never hardcode IDs, always find them via list/search
• Success phrase at the end — e.g., "Say 'Workflow completed successfully'"
• Be explicit — don't assume the LLM knows relationships between tools
• Use actual tool names — reference the exact tool names in the tools array

Compile after creating: npm run compile. Fix errors before continuing.

Step 6: Build and Run

Build first (required — evals test against dist/):

npm run build

Then run the eval tests for this collection:

npm run test:evals -- --testPathPatterns="{collection}"

If tests fail

1. Check build output — did dist/index.js get created?
2. Check verbose output — what did the LLM try to do?
3. Common fixes:
   • Tool not found — check tool names match exactly (use names from collection index)
   • LLM ignores instructions — make the prompt MORE explicit
   • Timeout — increase defaultMaxTurns or simplify the prompt
   • Budget exceeded — simplify the workflow or increase defaultMaxBudgetUsd
   • Create returns void — add a search/list step after create to find the ID
4. Update the prompt and re-run. Do NOT move to the next collection while tests fail.

Step 7: Next Collection

Repeat steps 1-6 for the next collection in .discover.json.

Step 8: Final Verification

After all collections have eval tests:

npm run build

npm run test:evals

Then run /count-mcp-tools to confirm all collections have evals. All collections should show "yes" in the Evals column. If any show "no", note which collections are missing eval tests (may be acceptable for some collections).

Report what was generated:

• Number of collections with eval tests
• Number of eval test files per collection
• Workflow types tested (CRUD, read-only, search, hierarchy)
• Any collections skipped (already had eval tests)
• Any test failures that need attention

File Structure

After running, the eval tests directory should contain:

tests/evals/
├── jest.config.ts                    # Separate Jest config for evals
├── helpers/
│   └── e2e-setup.ts                  # configureEvals setup (loaded via setupFilesAfterEnv)
├── {collection}-crud.test.ts         # CRUD lifecycle test (if applicable)
├── {collection}-read.test.ts         # Read-only test (if applicable)
└── ...

Next Steps

After eval tests pass:

• Disable verbose: true in test files for cleaner CI output
• Run /mcp-testing for reference on advanced eval patterns
• Use eval feedback to improve tool descriptions and schemas (Phase 5.3 in the development loop)