Perplexity AI MCP #131

This error occurs because your JSON Schema uses the Draft-07 dialect ("$schema": "http://json-schema.org/draft-07/schema#"), but the Ajv validator instance you're using is configured to only support JSON Schema 2020-12. stackoverflow

Why this happens

Ajv 8.x defaults to JSON Schema 2020-12, while older versions (Ajv 6.x) default to Draft-07. When you declare a Draft-07 schema but use a 2020-12 validator without proper configuration, Ajv rejects the $schema keyword as an "unsupported dialect." stackoverflow

How to fix it

You have two options:

Option 1: Use a pre-configured Ajv instance for Draft-07

If you want to keep using Draft-07 schemas, import and instantiate Ajv with the Draft-07 configuration:

// For Ajv 8.x with Draft-07 support
import Ajv from 'ajv/dist/2020'; // or appropriate import
const ajv = new Ajv({ strict: false });
// Add the draft-07 metaschema explicitly
ajv.addSchema(require('ajv/dist/refs/json-schema-draft-07.json'));

Or use the dedicated Draft-07 build if available in your Ajv version. stackoverflow

Option 2: Migrate your schema to JSON Schema 2020-12

Update your schema's $schema declaration to use the 2020-12 dialect:

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

Note that 2020-12 schemas don't use the trailing # in the URI (unlike Draft-07). jsonic

If your schema uses tuple validation (array form of items), you'll also need to:

• Rename items (when it's an array) to prefixItems
• Replace additionalItems with items or items: false jsonic

Option 3: Configure Ajv to accept multiple dialects

You can configure Ajv to be more permissive with schema dialects:

import Ajv2020 from 'ajv/dist/2020';
const ajv = new Ajv2020({ strict: false, strictSchema: false });

This disables strict mode checks that would otherwise reject unknown keywords or dialects. jsonic

Quick checklist

• Check your Ajv version (npm list ajv)
• Verify your import statement matches your intended draft (e.g., ajv/dist/2020 for 2020-12) stackoverflow
• Either update your schema's $schema URI or configure Ajv to support Draft-07
• Test validation with sample data after making changes

Would you like help with a specific migration step or configuration?