How do I install the Schema Check skill?

Run npx skillmds@latest add mearman/schema-check in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

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Who published Schema Check?

Mearman (@mearman) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Schema Check by mearman — Agent Skill

Name: Schema Check
Author: Mearman

Schema Check

Validate a JSON file against the schema referenced in its $schema property. Use when the user asks to check JSON against its own schema, validate self-describing JSON, auto-validate JSON files, or verify JSON with embedded schema reference.

Mearman 7affdc4 2.8 KB Updated Sep 17, 2026

File contents

Validate JSON Against Embedded $schema

Validate a JSON file against the schema referenced in its $schema property. This is useful for self-describing JSON documents that declare their own schema.

Usage

npx tsx scripts/check.ts <json-file> [options]

Arguments

Argument	Required	Description
`json-file`	Yes	Path to the JSON file with `$schema` property

Options

Option	Description
`--all-errors`	Report all errors, not just the first
`--no-cache`	Bypass cache when fetching remote schemas
`--strict`	Enable strict mode validation
`--verbose`	Show detailed validation output
`--format`	Output format: text (default), json

Output

Valid JSON:

Valid
  Schema: https://json-schema.org/draft/2020-12/schema
  File: my-schema.json

Invalid JSON:

Invalid (2 errors)
  Schema: ./schemas/config.schema.json
  1. /settings/timeout: must be number
  2. /settings/retries: must be >= 0

No schema reference:

Error: No $schema property found in config.json
  Hint: Use schema-validate to validate against a specific schema

Script Execution

npx tsx scripts/check.ts config.json
npx tsx scripts/check.ts config.json --all-errors
npx tsx scripts/check.ts config.json --no-cache --verbose

Run from the json-schema plugin directory: ~/.claude/plugins/cache/json-schema/

Schema Resolution

The $schema property can reference:

Remote URLs - Fetched and cached (24h TTL)

{ "$schema": "https://json-schema.org/draft/2020-12/schema" }

Local file paths - Resolved relative to the JSON file
```
{ "$schema": "./schemas/config.schema.json" }
```

Absolute paths

{ "$schema": "/Users/joe/schemas/config.schema.json" }

Common $schema Values

Schema URI	Description
`https://json-schema.org/draft/2020-12/schema`	JSON Schema Draft 2020-12
`https://json-schema.org/draft/2019-09/schema`	JSON Schema Draft 2019-09
`http://json-schema.org/draft-07/schema#`	JSON Schema Draft 7
`http://json-schema.org/draft-06/schema#`	JSON Schema Draft 6
`http://json-schema.org/draft-04/schema#`	JSON Schema Draft 4

Caching

Remote schemas are cached for 24 hours using the OS temporary directory. Use --no-cache to bypass caching and fetch fresh schemas.

Related Skills

Use schema-meta to validate that a schema is well-formed
Use schema-validate to validate JSON against an arbitrary schema file

---name: schema-checkdescription: Validate a JSON file against the schema referenced in its $schema property. Use when the user asks to check JSON against its own schema, validate self-describing JSON, auto-validate JSON files, or verify JSON with embedded schema reference.---# Validate JSON Against Embedded $schemaValidate a JSON file against the schema referenced in its `$schema` property. This is useful for self-describing JSON documents that declare their own schema.## Usage```bashnpx tsx scripts/check.ts <json-file> [options]```### Arguments| Argument | Required | Description ||----------|----------|-------------|| `json-file` | Yes | Path to the JSON file with `$schema` property |### Options| Option | Description ||--------|-------------|| `--all-errors` | Report all errors, not just the first || `--no-cache` | Bypass cache when fetching remote schemas || `--strict` | Enable strict mode validation || `--verbose` | Show detailed validation output || `--format` | Output format: text (default), json |### OutputValid JSON:```Valid Schema: https://json-schema.org/draft/2020-12/schema File: my-schema.json```Invalid JSON:```Invalid (2 errors) Schema: ./schemas/config.schema.json 1. /settings/timeout: must be number 2. /settings/retries: must be >= 0```No schema reference:```Error: No $schema property found in config.json Hint: Use schema-validate to validate against a specific schema```## Script Execution```bashnpx tsx scripts/check.ts config.jsonnpx tsx scripts/check.ts config.json --all-errorsnpx tsx scripts/check.ts config.json --no-cache --verbose```Run from the json-schema plugin directory: `~/.claude/plugins/cache/json-schema/`## Schema ResolutionThe `$schema` property can reference:1. **Remote URLs** - Fetched and cached (24h TTL) ```json { "$schema": "https://json-schema.org/draft/2020-12/schema" } ```2. **Local file paths** - Resolved relative to the JSON file ```json { "$schema": "./schemas/config.schema.json" } ```3. **Absolute paths** ```json { "$schema": "/Users/joe/schemas/config.schema.json" } ```## Common $schema Values| Schema URI | Description ||------------|-------------|| `https://json-schema.org/draft/2020-12/schema` | JSON Schema Draft 2020-12 || `https://json-schema.org/draft/2019-09/schema` | JSON Schema Draft 2019-09 || `http://json-schema.org/draft-07/schema#` | JSON Schema Draft 7 || `http://json-schema.org/draft-06/schema#` | JSON Schema Draft 6 || `http://json-schema.org/draft-04/schema#` | JSON Schema Draft 4 |## CachingRemote schemas are cached for 24 hours using the OS temporary directory. Use `--no-cache` to bypass caching and fetch fresh schemas.## Related Skills- Use `schema-meta` to validate that a schema is well-formed- Use `schema-validate` to validate JSON against an arbitrary schema file

Frequently asked questions