mcp_batch_create_content fails with schema validation error for complex objects

Hi!

First, thanks for your great module and the amazing list of tools you're shipping. I've been playing with the batch capabilities and faced an issue when trying to create nodes in batch with Claude Desktop using the STDIO server.

Below is the issue description (with the help of Claude!):

Problem

The mcp_batch_create_content tool cannot create content with fields. It fails with a schema validation error before reaching the PHP code.

Error:

validation_errors: [{
  "message": "The data ({type}) must match the type: {expected}",
  "keyword": "type",
  "path": "items.0"
}]

Root Cause

In ToolApiSchemaConverter::inputDefinitionToSchema() (line 173), when data_type: 'list' is used without a ListInputDefinition, the default schema is:

$schema['items'] = ['type' => 'string'];

This rejects complex objects like {"title": "...", "fields": {...}}.

Solution

1. Change data_type: 'list' → data_type: 'any' in input definitions
2. Add JSON decoding in executeLegacy() since MCP passes complex types as JSON strings
3. Strengthen validation to ensure the decoded value is an array

Testing

✅ Tested with 5 items containing body + entity reference fields

✅ Tested with 50 items (maximum limit)

✅ 0 errors in both cases

Files Changed

• modules/mcp_tools_batch/src/Plugin/tool/Tool/CreateMultipleContent.php

Additional Notes

• mcp_batch_create_terms works by chance because terms can be simple strings
• The same issue likely affects mcp_batch_update_content and other batch tools with complex inputs
• Render cache invalidation after batch creation may need separate investigation

A merge request will follow shortly.