json-schema-lookup

name	json-schema-lookup
description	Guidelines for querying schemastore.org. Use when you need to validate or discover options for config files relating to popular open source projects.
allowed-tools	WebFetch Bash(curl *) Bash(jq *) Bash(yq *) Bash(grep *) Bash(head *) Bash(less *)

JSON Schema Lookup via SchemaStore

Query schemastore.org's catalog of public configuration file schemas to validate structure, discover options, and check allowed values.

API

• Catalog: https://www.schemastore.org/api/json/catalog.json
  • Structure: { "schemas": [{ "name", "description", "fileMatch", "url", "versions"? }] }
• Individual schemas: Fetch the url from the matching catalog entry

Workflow

1. Find the schema

Search the catalog by name or filename pattern:

# Search by name (case-insensitive)
curl -s https://www.schemastore.org/api/json/catalog.json | jq '.schemas[] | select(.name | test("tsconfig"; "i")) | {name, url, fileMatch}'

# Search by filename match
curl -s https://www.schemastore.org/api/json/catalog.json | jq '.schemas[] | select(.fileMatch[]? | test("package\\.json")) | {name, url}'

Alternatively, use WebFetch on the catalog URL and ask for the relevant entry.

2. Fetch and inspect the schema

# List top-level properties
curl -s SCHEMA_URL | jq '.properties | keys'

# Inspect a specific field (type, enum values, description)
curl -s SCHEMA_URL | jq '.properties.FIELD_NAME'

# Check definitions/shared types (schemas use $ref to these)
curl -s SCHEMA_URL | jq '.definitions.DEF_NAME.properties'

# Get the full schema (warning - might be large!)
curl -s SCHEMA_URL | jq .

3. Common queries

# Find enum values for a field
curl -s SCHEMA_URL | jq '.properties.FIELD.enum'

# List nested properties (e.g. compilerOptions in tsconfig)
curl -s SCHEMA_URL | jq '.definitions.compilerOptionsDefinition.properties.compilerOptions.properties | keys'

# Find all required fields
curl -s SCHEMA_URL | jq '.required'

Tips

• Some schemas use allOf/anyOf composition -- check those arrays for the full property set
• The versions field on catalog entries provides version-specific schema URLs when available
• Schema URLs vary: some point to json.schemastore.org, others to raw.githubusercontent.com
• For large schemas, query specific paths rather than dumping the entire document
• Cache the catalog response locally if making multiple lookups in one session