MCP Adapter v0.3.0 is now available. This package is the official WordPress integration for the Model Context Protocol (MCP), exposing WordPress abilities (registered via the Abilities API) as MCP tools, resources, and prompts that AI agents can discover and invoke.
Where earlier releases established the core adapter and architecture, 0.3.0 focuses on transport, observability, and error‑handling improvements, and aligns the adapter with the Abilities API v0.4.0 and the latest MCP HTTP specification.
What the MCP Adapter does
The MCP Adapter sits between WordPress and MCP clients (agents, IDEs, assistants) and:
- Converts WordPress abilities into MCP tools, resources, and prompts.
- Supports multiple MCP servers with different configurations from one WordPress site.
- Provides HTTP and STDIO transports, as well as an interface for custom transports.
- Includes validation, permissions, observability, and WP‑CLI integration, enabling MCP servers to run locally or in production.
It is part of the AI Building Blocks for WordPress, alongside the Abilities API, PHP/WP AI Client, and the AI Experiments plugin.
Highlights in v0.3.0
Version 0.3.0 introduces several breaking changes and new capabilities:
- Unified observability model
- All events now share a single event name (for example, mcp.request) with a status tag indicating success or failure, instead of separate success and failure-specific event names.
- Observability handlers are now instance‑based and use a single record_event() method that can capture both events and timings via the McpObservabilityHandlerInterface.
- New HTTP transport layer
- The previous RestTransport and StreamableTransport implementations have been replaced by a single HttpTransport class that implements the 2025‑06‑18 MCP HTTP specification, sessions, and JSON‑RPC response handling (streaming will come in later versions).
- WP_Error‑based error handling
- Error handling has been refactored across handlers to use WP_Error consistently instead of exceptions.
- Tool and resource errors now conform to the MCP error response format, improving interoperability with MCP clients.
- Standardized hook names
- All plugin hooks are now prefixed with mcp_adapter_ for consistency, replacing older hook names such as mcp_validation_enabled.
- Documentation and tooling
- A dedicated migration guide (docs/migration/v0.3.0.md) walks through code updates for observability handlers, transports, and hooks.
- Documentation has been expanded for transport permissions, custom transports, and error‑handling patterns; CI and static analysis tooling have also been updated.
- Bug fixes and robustness improvements
- Fixes include preventing metadata from leaking into tool responses, improving handling of null and falsy parameters, and tightening validation for abilities without input schemas.
Migration notes for existing users
If you are already running an MCP server with the adapter, upgrading to 0.3.0 requires a few targeted changes:
1. Update observability handlers
- Switch from static helper methods to instance methods implementing McpObservabilityHandlerInterface.
- Replace any usage of a dedicated error event helper (record_error_event‑style methods) with a call to record_event() that includes status, error category, and any timing information.
2. Update transport configuration
- Replace references to RestTransport or StreamableTransport in your server configuration with HttpTransport.
Example:
use WP\MCP\Transport\HttpTransport;
$adapter->create_server(
'my-server',
'my-namespace',
'mcp',
'My MCP Server',
'Description',
'1.0.0',
[ HttpTransport::class ],
\WP\MCP\Infrastructure\ErrorHandling\ErrorLogMcpErrorHandler::class
);
3. Rename hooks to the new prefix
- Update any filters or actions you register to use the mcp_adapter_… hook names, for example:
add_filter(
'mcp_adapter_validation_enabled',
__return_true()
);
The migration guide in the repository provides detailed examples and is the recommended reference for updating existing deployments.
Where to go next
- MCP Adapter GitHub repository and documentation: architecture overview, examples, and migration guides.
- MCP Adapter overview post on the Make/Core AI blog for broader context and use‑cases.
- Abilities API and WP AI Client SDK documentation, to see how abilities, the MCP Adapter, and the SDK form a cohesive layer for AI integrations across WordPress.
These recent releases together move the AI building blocks closer to a complete end‑to‑end stack: WordPress can describe what it can do, expose those abilities to MCP‑compatible tools, and call out to external AI providers from plugins and themes using a unified client.