Agent skill

Warehouse Init

by astronomer in astronomer/agents

Initialize warehouse schema discovery. An agent skill from astronomer/agents.

Apache-2.0Auto-check passedDatabases

Install Warehouse Init

skills CLI
$ npx skills add astronomer/agents --skill warehouse-init -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install astronomer/agents warehouse-init --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/astronomer/agents.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/warehouse-init .claude/skills/warehouse-init && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
warehouse-init
GitHub stars
451
Token cost
~2.7k tokens
SKILL.md length
582 words
Files
1
Skills in repo
34
Repo updated
First seen
Licence
Apache-2.0

At a glance

Initialize warehouse schema discovery. An agent skill from astronomer/agents.

  • Works in 8 steps: Read Warehouse Configuration → Search Codebase for Context (Parallel) → Parallel Warehouse Discovery → …
  • User says /astronomer-data:warehouse-init
  • SKILL.md covers What This Does, Process, Output Format and Command Options, plus 5 more sections
  • Calls uv

What it does

Warehouse Init is an agent skill from astronomer/agents. Initialize warehouse schema discovery. Generates .astro/warehouse.md with all table metadata for instant lookups. Run once per project, refresh when schema changes. Use when user says "/astronomer-data:warehouse-init" or asks to set up data discovery.

Its SKILL.md is about 2.7k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Databases, covering Static sites and blogs, Data warehousing and Data pipelines and ETL. It works with Astro. The repository describes itself as: AI agent tooling for data engineering workflows. The licence is Apache-2.0.

When your agent uses it

  • User says /astronomer-data:warehouse-init
  • Asks to set up data discovery

Example prompts

  • “/astronomer-data:warehouse-init”
  • “/warehouse-init”

Requirements

  • A credential in PRIMARY_KEY

Workflow steps

8 steps, taken from the step headings in SKILL.md.

  1. Read Warehouse Configuration
  2. Search Codebase for Context (Parallel)
  3. Parallel Warehouse Discovery
  4. Discover Categorical Value Families
  5. Merge Results
  6. Generate warehouse.md
  7. Pre-populate Cache
  8. Offer CLAUDE.md Integration (Ask User)

What it can do on your machine

Read from SKILL.md and the folder at commit 486ee63. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Shell commands in SKILL.md call:

    • uv

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md. Its commands use uv, which can reach the network depending on how they are called.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Warehouse Init loads about 2.7k tokens when it runs. Until then it costs about 67 tokens; SKILL.md has 582 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~67
When it runs · the whole SKILL.md, loaded when a task matches
~2.7k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from astronomer/agents at commit 486ee63, republished under its Apache-2.0 licence (© astronomer). 582 words, ~2,673 tokens.

Download SKILL.mdSave it as .claude/skills/warehouse-init/SKILL.md (or your agent's skills folder).
name
warehouse-init
description
Initialize warehouse schema discovery. Generates .astro/warehouse.md with all table metadata for instant lookups. Run once per project, refresh when schema changes. Use when user says "/astronomer-data:warehouse-init" or asks to set up data discovery.

Initialize Warehouse Schema

Generate a comprehensive, user-editable schema reference file for the data warehouse.

Scripts: ../analyzing-data/scripts/ — All CLI commands below are relative to the analyzing-data skill's directory. Before running any scripts/cli.py command, cd to ../analyzing-data/ relative to this file.

What This Does

  1. Discovers all databases, schemas, tables, and columns from the warehouse
  2. Enriches with codebase context (dbt models, gusty SQL, schema docs)
  3. Records row counts and identifies large tables
  4. Generates .astro/warehouse.md - a version-controllable, team-shareable reference
  5. Enables instant concept→table lookups without warehouse queries

Process

Step 1: Read Warehouse Configuration
bash
cat ~/.astro/agents/warehouse.yml

Get the list of databases to discover (e.g., databases: [HQ, ANALYTICS, RAW]).

Step 2: Search Codebase for Context (Parallel)

Launch a subagent to find business context in code:

Task(
    subagent_type="Explore",
    prompt="""
    Search for data model documentation in the codebase:

    1. dbt models: **/models/**/*.yml, **/schema.yml
       - Extract table descriptions, column descriptions
       - Note primary keys and tests

    2. Gusty/declarative SQL: **/dags/**/*.sql with YAML frontmatter
       - Parse frontmatter for: description, primary_key, tests
       - Note schema mappings

    3. AGENTS.md or CLAUDE.md files with data layer documentation

    Return a mapping of:
      table_name -> {description, primary_key, important_columns, layer}
    """
)
Step 3: Parallel Warehouse Discovery

Launch one subagent per database using the Task tool:

For each database in configured_databases:
    Task(
        subagent_type="general-purpose",
        prompt="""
        Discover all metadata for database {DATABASE}.

        Use the CLI to run SQL queries:
        # Scripts are relative to ../analyzing-data/
        uv run scripts/cli.py exec "df = run_sql('...')"
        uv run scripts/cli.py exec "print(df)"

        1. Query schemas:
           SELECT SCHEMA_NAME FROM {DATABASE}.INFORMATION_SCHEMA.SCHEMATA

        2. Query tables with row counts:
           SELECT TABLE_SCHEMA, TABLE_NAME, ROW_COUNT, COMMENT
           FROM {DATABASE}.INFORMATION_SCHEMA.TABLES
           ORDER BY TABLE_SCHEMA, TABLE_NAME

        3. For important schemas (MODEL_*, METRICS_*, MART_*), query columns:
           SELECT TABLE_NAME, COLUMN_NAME, DATA_TYPE, COMMENT
           FROM {DATABASE}.INFORMATION_SCHEMA.COLUMNS
           WHERE TABLE_SCHEMA = 'X'

        Return a structured summary:
        - Database name
        - List of schemas with table counts
        - For each table: name, row_count, key columns
        - Flag any tables with >100M rows as "large"
        """
    )

Run all subagents in parallel (single message with multiple Task calls).

Step 4: Discover Categorical Value Families

For key categorical columns (like OPERATOR, STATUS, TYPE, FEATURE), discover value families:

bash
uv run cli.py exec "df = run_sql('''
SELECT DISTINCT column_name, COUNT(*) as occurrences
FROM table
WHERE column_name IS NOT NULL
GROUP BY column_name
ORDER BY occurrences DESC
LIMIT 50
''')"
uv run cli.py exec "print(df)"

Group related values into families by common prefix/suffix (e.g., Export* for ExportCSV, ExportJSON, ExportParquet).

Step 5: Merge Results

Combine warehouse metadata + codebase context:

  1. Quick Reference table - concept → table mappings (pre-populated from code if found)
  2. Categorical Columns - value families for key filter columns
  3. Database sections - one per database
  4. Schema subsections - tables grouped by schema
  5. Table details - columns, row counts, descriptions from code, warnings
Step 6: Generate warehouse.md

Write the file to:

  • .astro/warehouse.md (default - project-specific, version-controllable)
  • ~/.astro/agents/warehouse.md (if --global flag)

Output Format

markdown
# Warehouse Schema

> Generated by `/astronomer-data:warehouse-init` on {DATE}. Edit freely to add business context.

## Quick Reference

| Concept | Table | Key Column | Date Column |
|---------|-------|------------|-------------|
| customers | HQ.MODEL_ASTRO.ORGANIZATIONS | ORG_ID | CREATED_AT |
<!-- Add your concept mappings here -->

## Categorical Columns

When filtering on these columns, explore value families first (values often have variants):

| Table | Column | Value Families |
|-------|--------|----------------|
| {TABLE} | {COLUMN} | `{PREFIX}*` ({VALUE1}, {VALUE2}, ...) |
<!-- Populated by /astronomer-data:warehouse-init from actual warehouse data -->

## Data Layer Hierarchy

Query downstream first: `reporting` > `mart_*` > `metric_*` > `model_*` > `IN_*`

| Layer | Prefix | Purpose |
|-------|--------|---------|
| Reporting | `reporting.*` | Dashboard-optimized |
| Mart | `mart_*` | Combined analytics |
| Metric | `metric_*` | KPIs at various grains |
| Model | `model_*` | Cleansed sources of truth |
| Raw | `IN_*` | Source data - avoid |

## {DATABASE} Database

### {SCHEMA} Schema

#### {TABLE_NAME}
{DESCRIPTION from code if found}

| Column | Type | Description |
|--------|------|-------------|
| COL1 | VARCHAR | {from code or inferred} |

- **Rows:** {ROW_COUNT}
- **Key column:** {PRIMARY_KEY from code or inferred}
{IF ROW_COUNT > 100M: - **⚠️ WARNING:** Large table - always add date filters}

## Relationships

{Inferred relationships based on column names like *_ID}

Command Options

OptionEffect
/astronomer-data:warehouse-initGenerate .astro/warehouse.md
/astronomer-data:warehouse-init --refreshRegenerate, preserving user edits
/astronomer-data:warehouse-init --database HQOnly discover specific database
/astronomer-data:warehouse-init --globalWrite to ~/.astro/agents/ instead
Step 7: Pre-populate Cache

After generating warehouse.md, populate the concept cache:

bash
# Scripts are relative to ../analyzing-data/
uv run cli.py concept import -p .astro/warehouse.md
uv run cli.py concept learn customers HQ.MART_CUST.CURRENT_ASTRO_CUSTS -k ACCT_ID
Step 8: Offer CLAUDE.md Integration (Ask User)

Ask the user:

Would you like to add the Quick Reference table to your CLAUDE.md file?

This ensures the schema mappings are always in context for data queries, improving accuracy from ~25% to ~100% for complex queries.

Options:

  1. Yes, add to CLAUDE.md (Recommended) - Append Quick Reference section
  2. No, skip - Use warehouse.md and cache only

If user chooses Yes:

  1. Check if .claude/CLAUDE.md or CLAUDE.md exists
  2. If exists, append the Quick Reference section (avoid duplicates)
  3. If not exists, create .claude/CLAUDE.md with just the Quick Reference

Quick Reference section to add:

markdown
## Data Warehouse Quick Reference

When querying the warehouse, use these table mappings:

| Concept | Table | Key Column | Date Column |
|---------|-------|------------|-------------|
{rows from warehouse.md Quick Reference}

**Large tables (always filter by date):** {list tables with >100M rows}

> Auto-generated by `/astronomer-data:warehouse-init`. Run `/astronomer-data:warehouse-init --refresh` to update.

If yes: Append the Quick Reference section to .claude/CLAUDE.md or CLAUDE.md.

Show full SKILL.md (178 more words)Show less

After Generation

Tell the user:

Generated .astro/warehouse.md

Summary:
  - {N} databases, {N} schemas, {N} tables
  - {N} tables enriched with code descriptions
  - {N} concepts cached for instant lookup

Next steps:
  1. Edit .astro/warehouse.md to add business context
  2. Commit to version control
  3. Run /astronomer-data:warehouse-init --refresh when schema changes

Refresh Behavior

When --refresh is specified:

  1. Read existing warehouse.md
  2. Preserve all HTML comments (<!-- ... -->)
  3. Preserve Quick Reference table entries (user-added)
  4. Preserve user-added descriptions
  5. Update row counts and add new tables
  6. Mark removed tables with <!-- REMOVED --> comment

Cache Staleness & Schema Drift

The runtime cache has a 7-day TTL by default. After 7 days, cached entries expire and will be re-discovered on next use.

When to Refresh

Run /astronomer-data:warehouse-init --refresh when:

  • Schema changes: Tables added, renamed, or removed
  • Column changes: New columns added or types changed
  • After deployments: If your data pipeline deploys schema migrations
  • Weekly: As a good practice, even if no known changes
Signs of Stale Cache

Watch for these indicators:

  • Queries fail with "table not found" errors
  • Results seem wrong or outdated
  • New tables aren't being discovered
Manual Cache Reset

If you suspect cache issues:

bash
# Scripts are relative to ../analyzing-data/
uv run scripts/cli.py cache status
uv run scripts/cli.py cache clear --stale-only
uv run scripts/cli.py cache clear

Codebase Patterns Recognized

PatternSourceWhat We Extract
**/models/**/*.ymldbttable/column descriptions, tests
**/dags/**/*.sqlgustyYAML frontmatter (description, primary_key)
AGENTS.md, CLAUDE.mddocsdata layer hierarchy, conventions
**/docs/**/*.mddocsbusiness context

Example Session

User: /astronomer-data:warehouse-init

Agent:
→ Reading warehouse configuration...
→ Found 1 warehouse with databases: HQ, PRODUCT

→ Searching codebase for data documentation...
  Found: AGENTS.md with data layer hierarchy
  Found: 45 SQL files with YAML frontmatter in dags/declarative/

→ Launching parallel warehouse discovery...
  [Database: HQ] Discovering schemas...
  [Database: PRODUCT] Discovering schemas...

→ HQ: Found 29 schemas, 401 tables
→ PRODUCT: Found 1 schema, 0 tables

→ Merging warehouse metadata with code context...
  Enriched 45 tables with descriptions from code

→ Generated .astro/warehouse.md

Summary:
  - 2 databases
  - 30 schemas
  - 401 tables
  - 45 tables enriched with code descriptions
  - 8 large tables flagged (>100M rows)

Next steps:
  1. Review .astro/warehouse.md
  2. Add concept mappings to Quick Reference
  3. Commit to version control
  4. Run /astronomer-data:warehouse-init --refresh when schema changes

© astronomer, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in skills/warehouse-init of astronomer/agents.

Open the folder on GitHubat commit 486ee63

Compare with similar skills

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Snowflake Developmentsickn33/agentic-awesome-skills47k2 repos~2.1kAutomated safety check: PassMIT
Dbt Model Indexwarpdotdev/oz-skills825—~915Automated safety check: PassMIT
Snowflake Developmentalirezarezvani/claude-skills28k—~3.2kAutomated safety check: PassMIT
Modeling Dimension TablesPostHog/posthog40k—~1.4kAutomated safety check: PassCustom licence

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Works with

Questions about Warehouse Init

What does Warehouse Init do?

Initialize warehouse schema discovery. An agent skill from astronomer/agents. Warehouse Init is an agent skill from astronomer/agents. Initialize warehouse schema discovery.

When should I use Warehouse Init?

Warehouse Init fits situations like: user says /astronomer-data:warehouse-init; asks to set up data discovery.

How do I install Warehouse Init in Claude Code?

Run `npx skills add astronomer/agents --skill warehouse-init -a claude-code`. Or copy the skill folder (skills/warehouse-init in astronomer/agents) into .claude/skills/warehouse-init in your project. Claude Code loads it when a task matches its description.

How do I install Warehouse Init in Codex?

Run `npx skills add astronomer/agents --skill warehouse-init -a codex`. Or copy the skill folder (skills/warehouse-init in astronomer/agents) into .agents/skills/warehouse-init in your project. Codex loads it when a task matches its description.

Can I use Warehouse Init in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add astronomer/agents --skill warehouse-init -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/warehouse-init, .gemini/skills/warehouse-init, .github/skills/warehouse-init and .opencode/skills/warehouse-init in your project.

What does Warehouse Init need to run?

Going by SKILL.md and its folder, Warehouse Init needs the command-line tools its instructions call (uv). Our summary lists: A credential in PRIMARY_KEY.

Does Warehouse Init access the network?

SKILL.md contains no URLs. Its commands use uv, which can reach the network depending on how they are called. This is read from the text; nothing was executed.

Is Warehouse Init safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Warehouse Init use?

Warehouse Init is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Warehouse Init use?

About 2.7k tokens (SKILL.md is roughly 11k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Warehouse Init?

Skills that share tags, products or a category with Warehouse Init: Clickhouse Io (hellangleZ/burn-in-cceverywhere-ralph, 112 stars), Snowflake Development (sickn33/agentic-awesome-skills, 47k stars), Dbt Model Index (warpdotdev/oz-skills, 825 stars) and Snowflake Development (alirezarezvani/claude-skills, 28k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Warehouse Init?

astronomer (a GitHub organization) maintains it in astronomer/agents, which has 451 GitHub stars. The repository holds 34 skills in this directory. The repository was last updated on October 7, 2026.

Source: astronomer/agents on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.