Create a Seed Skill

Scaffold an integration-type skill from scratch. A seed skill is SKILL.md + reference assets + prompts.jsonl entries that together teach an agent to sprout a working, testable integration.

When to Use This

Integration skills (use this skill):

• Wrapping an SDK or framework with code generation + real API tests

• The eval question is: "Did the agent write code that calls real APIs and passes tests?"

• Examples: ydc-ai-sdk-integration , teams-anthropic-integration

Tool skills (do NOT use this skill):

• CLI wrappers where the agent runs a command, not writes code

• No test directory, no generated files

• Examples: youdotcom-cli

Decision Point

Ask the developer first:

Is this an integration skill (the agent generates code + tests) or a tool skill (the agent runs a CLI command)?

• Integration → Continue with this workflow

• Tool → Stop. This skill is not needed for tool skills.

Workflow

Step 1 — Gather Information

Ask these questions all at once (do not ask one by one):

• Skill name: What should it be called? (lowercase, hyphens, e.g. my-sdk-integration )

• Package(s): What npm/pip package(s) does it wrap? Include exact package names.

• Language(s): TypeScript, Python, or both?

• Both means: separate asset files for each language, two prompts.jsonl entries (one -typescript , one -python ), and two tests/ directories (tests/<skill-name>-typescript/ and tests/<skill-name>-python/ ), each with a .gitkeep file.

• One language means: one set of assets, one prompts.jsonl entry, one tests/<skill-name>/ directory with a .gitkeep file.

• Path A (basic): What is the simplest working integration — one function, one API call?

• Path B (extended): What is the natural extension — MCP, streaming, tool filtering, etc.?

• Required env vars: Which API keys are required? (e.g. MY_API_KEY , OPENAI_API_KEY )

• Test query: What is a factual question with a deterministic, multi-keyword answer that the integration should be able to answer? (See Choosing a Test Query)

Step 2 — Read Reference Assets

Before writing any code, read the reference assets to understand the required structure:

• assets/example-SKILL.md — complete SKILL.md template

• assets/example-path-a.ts — TypeScript Path A asset structure

• assets/example-test.spec.ts — TypeScript test asset structure

• assets/example-pyproject.toml — Python project config asset

• assets/example-test_integration.py — Python test asset structure

Step 3 — Create Files

Create all files in one pass. The skill lives in skills/<skill-name>/ .

Directory layout:

skills/<skill-name>/ ├── SKILL.md └── assets/ # TypeScript: ├── path-a-<variant>.ts # Path A integration ├── path-b-<variant>.ts # Path B integration (if applicable) ├── integration.spec.ts # Bun test file # Python: ├── path_a_<variant>.py # Path A integration ├── path_b_<variant>.py # Path B integration (if applicable) ├── test_integration.py # pytest file └── pyproject.toml # Python project config (required for uv run pytest)

Also create (see below):

tests/<skill-name>/ # single language └── .gitkeep

— or for both languages —

tests/<skill-name>-typescript/ └── .gitkeep tests/<skill-name>-python/ └── .gitkeep

Also create the tests/ eval target directory (or directories) with a .gitkeep file so the directory exists in git before agents write to it:

• Single language: tests/<skill-name>/.gitkeep

• Both languages: tests/<skill-name>-typescript/.gitkeep and tests/<skill-name>-python/.gitkeep

Single language (adjust path as needed):

mkdir -p tests/<skill-name> && touch tests/<skill-name>/.gitkeep

Both languages:

mkdir -p tests/<skill-name>-typescript tests/<skill-name>-python touch tests/<skill-name>-typescript/.gitkeep tests/<skill-name>-python/.gitkeep

Step 4 — Add prompts.jsonl Entry

Append one entry per language to data/prompts/prompts.jsonl .

Single language template (pick one concrete example — do NOT leave TypeScript or Python as a placeholder):

TypeScript:

{"id":"<skill-name>","input":["Using the <skill-name> skill, create a working TypeScript <description of Path A> integration. Write flat minimal code with no comments or TSDoc. Write integration tests that call real APIs and assert on meaningful response content. Save everything to the tests/<skill-name> directory.","Extend the integration with <description of Path B>. Write flat minimal code with no comments or TSDoc. Update the integration tests to verify the extended integration also works with a live query."],"metadata":{"cwd":"tests/<skill-name>","language":"typescript"}}

Python:

{"id":"<skill-name>","input":["Using the <skill-name> skill, create a working Python <description of Path A> integration. Write flat minimal code with no comments or docstrings. Write integration tests that call real APIs and assert on meaningful response content. Save everything to the tests/<skill-name> directory.","Extend the integration with <description of Path B>. Write flat minimal code with no comments or docstrings. Update the integration tests to verify the extended integration also works with a live query."],"metadata":{"cwd":"tests/<skill-name>","language":"python"}}

Both languages — append TWO entries:

{"id":"<skill-name>-typescript","input":["Using the <skill-name> skill, create a working TypeScript <description of Path A> integration. Write flat minimal code with no comments or TSDoc. Write integration tests that call real APIs and assert on meaningful response content. Save everything to the tests/<skill-name>-typescript directory.","Extend the integration with <description of Path B>. Write flat minimal code with no comments or TSDoc. Update the integration tests to verify the extended integration also works with a live query."],"metadata":{"cwd":"tests/<skill-name>-typescript","language":"typescript"}} {"id":"<skill-name>-python","input":["Using the <skill-name> skill, create a working Python <description of Path A> integration. Write flat minimal code with no comments or docstrings. Write integration tests that call real APIs and assert on meaningful response content. Save everything to the tests/<skill-name>-python directory.","Extend the integration with <description of Path B>. Write flat minimal code with no comments or docstrings. Update the integration tests to verify the extended integration also works with a live query."],"metadata":{"cwd":"tests/<skill-name>-python","language":"python"}}

Rules for prompts:

• Exactly 2 turns per entry

• Name the language explicitly in Turn 1 ("TypeScript" or "Python") so the agent doesn't guess

• Describe outcomes only — never mention class names, method names, or config keys

• Turn 1: basic integration + tests

• Turn 2: extension + update tests

• metadata.cwd must match the tests/ directory created in Step 3 (the grader reads files from here)

• metadata.language must be typescript or python

Step 5 — Create Symlink

ln -s ../../skills/<skill-name> .claude/skills/<skill-name>

Step 6 — Validate

bunx @plaited/development-skills validate-skill skills/<skill-name>

What Makes a Good Seed Skill

SKILL.md Must Contain

• Correct frontmatter — name , description , license , compatibility , allowed-tools , assets list, metadata

• Decision point — brief Path A vs Path B description, one clear question

• Install instructions — exact package name and install command

• Complete code templates — full working examples, not pseudo-code

• Security section — if the integration fetches untrusted web content, include prompt injection warning (W011)

• Generate Integration Tests section — markdown links to all asset files, explicit rules

Generate Integration Tests Rules (include all of these)

Rules:

• No mocks — call real APIs
• Assert on keywords from a deterministic query, not just length > 0
• Validate required env vars at test start (inside the test function, not at module scope)
• TypeScript: use bun:test, dynamic imports inside tests, timeout: 60_000
• Python: use pytest, import inside test function; always include pyproject.toml with pytest in [dependency-groups] dev
• Run TypeScript tests: bun test | Run Python tests: uv run pytest

Reference Assets Must

• Compile and run — no pseudo-code, no placeholders

• Include security instructions in agent instructions /system_prompt

• Use the test query from Step 1 in both the integration files (as the main example) and the test assertions

• Assert on keywords — not just length > 0

• TypeScript: export a callable function, use dynamic import() in tests

• Python: define a main(query: str) -> str function, use deferred imports inside test functions

Choosing a Test Query

The real goal: verify the integration code ran, not that the LLM knows the answer.

Most LLMs can answer factual questions from memory without calling any tool. A query the model can answer without searching doesn't prove the MCP server or SDK tool was invoked — the integration may silently skip the tool and still pass.

What actually matters: the test passes only if the code path worked — the SDK was initialized, the MCP server was reached, and a response was returned. A keyword assertion that matches typical tool output is better than no assertion, but it doesn't prove the tool fired.

Practical guidance:

• Prefix the query with an explicit instruction to use the tool — this forces invocation rather than relying on the model's judgment

• Use a query with a stable, multi-keyword answer so you can assert on content, not just length > 0

• The LLM-as-judge grader (scripts/grader.ts ) also evaluates the generated code structure, not just whether keywords appear

Good examples (explicit tool instruction + stable keywords):

• "Search the web for the three branches of the US government" → assert legislative , executive , judicial

• "Use web search to find what programming language TypeScript compiles to" → assert javascript

• "Search the web for the four classical elements" → assert earth , water , fire , air

The "Search the web for..." or "Use [tool name] to find..." prefix makes tool use an explicit instruction, not an inference — the model must call the tool to follow the prompt.

Avoid:

• Plain factual queries ("What are the three branches...") — model may answer from memory, skipping the tool entirely

• "What is the latest news in AI?" — changes daily, no predictable keywords

• "Say hello in one sentence." — no meaningful content assertion possible

Eval Grader Notes

The grader (scripts/grader.ts ) runs from metadata.cwd :

• TypeScript: runs bun test , scans **/*.{ts,js} for generated files

• Python: runs uv run pytest (requires pyproject.toml in the test dir)

• Sends test output + generated file contents to Haiku for LLM-as-judge scoring (0.0–1.0)

• Pass threshold is ~0.65; target is 0.95

Common failure modes to prevent in your SKILL.md:

• pytest missing: Always include pyproject.toml asset with pytest in dev deps

• Module-scope env checks: Python imports should be inside test functions to avoid collection errors

• Prescriptive prompts: prompts.jsonl should describe outcomes, not implementation steps

• Tool introspection: Never instruct agents to assert on SDK event streams or tool call objects

• open-ended test queries: "latest AI news" produces unpredictable content — use factual queries with deterministic keywords

Example: Adding a New Python Integration Skill

Given: wrapping the httpx library with You.com search, Python only.

Files to create:

skills/ydc-httpx-integration/ ├── SKILL.md └── assets/ ├── path_a_basic.py ├── test_integration.py └── pyproject.toml

tests/ydc-httpx-integration/ └── .gitkeep

Create the tests directory:

mkdir -p tests/ydc-httpx-integration && touch tests/ydc-httpx-integration/.gitkeep

prompts.jsonl entry:

{"id":"ydc-httpx-integration","input":["Using the ydc-httpx-integration skill, create a working Python application that calls the You.com search API directly with httpx and returns search results. Write integration tests that call the real API and verify the response contains expected keywords. Save everything to the tests/ydc-httpx-integration directory.","Extend the integration to also support content extraction from URLs. Update the integration tests to verify both search and content extraction work with live queries."],"metadata":{"cwd":"tests/ydc-httpx-integration","language":"python"}}