Try: Update wordpress/mcp-adapter to v0.5.0 (dev-trunk) - #64052

Submission Review Guidelines:

• I have followed the WooCommerce Contributing Guidelines and the WordPress Coding Standards.
• I have checked to ensure there aren't other open Pull Requests for the same update/change.
• I have reviewed my code for security best practices.
• Following the above guidelines will result in quick merges and clear and detailed feedback when appropriate.

Changes proposed in this Pull Request:

Updates the wordpress/mcp-adapter Composer dependency from ^0.3.0 to dev-trunk (upcoming v0.5.0). This is a draft for others to try the new adapter — not intended for merge yet.

What changed in the adapter:

• Typed protocol DTOs via new wordpress/php-mcp-schema ^0.1.0 dependency
• MCP spec updated from 2025-06-18 to 2025-11-25
• Interfaces moved from WP\MCP\Transport\Interfaces\ to WP\MCP\Transport\Contracts\
• HttpTransport::check_permission() now casts results to bool and uses fail-closed security (returns false on error)
• McpTransportContext constructor now validates required/optional keys strictly
• Composer package type changed from library to wordpress-plugin

What changed in WooCommerce:

• composer.json: Version bump + installer-paths override to keep the package in vendor/ (needed because the package type changed)
• composer.lock: Regenerated with new dependency tree
• No PHP code changes — all public APIs used by WooCommerce (McpAdapter::create_server(), HttpTransport, transport interfaces) are backward compatible

Pre-existing issues found during E2E testing (not caused by this update):

Full MCP Inspector E2E testing revealed issues that exist on trunk today and are unrelated to the adapter update:

1. Output schema validation failures (8 of 9 tools) — All product/order tools (except products-delete) fail strict schema validation because:

   • Date-time fields lack timezone suffix (2026-04-07T16:06:06 instead of RFC 3339 2026-04-07T16:06:06Z)
   • Nullable fields (date_on_sale_from, stock_quantity, date_paid, etc.) return null but schemas declare them as string/integer without allowing null
   • shipping_class_id schema says string, API returns integer
   • external_url and billing.email use format constraints (uri, email) but return empty strings

2. isError flag not set on error responses — When tools like products-get or orders-get receive a non-existent ID, the server returns the error payload but with isError: false. MCP clients rely on isError: true to distinguish errors from successful results.

These issues should be tracked and addressed in separate PRs.

How to test the changes in this Pull Request:

1. Check out this branch and run composer install from plugins/woocommerce/
2. Start wp-env: pnpm --filter=@woocommerce/plugin-woocommerce wp-env start
3. Enable the MCP feature: pnpm --filter=@woocommerce/plugin-woocommerce wp-env run cli wp option update woocommerce_feature_mcp_integration_enabled yes
4. Run unit tests:

   pnpm --filter=@woocommerce/plugin-woocommerce test:php:env -- --filter MCPAdapterProviderTest
   pnpm --filter=@woocommerce/plugin-woocommerce test:php:env -- --filter WooCommerceRestTransportTest
   

5. Verify all 25 tests pass (10 + 15)
6. For E2E testing, use the woocommerce-mcp-inspector skill or follow the manual steps:
   • Set up insecure transport mu-plugin (for local HTTP)
   • Create a WooCommerce API key
   • Run npx @modelcontextprotocol/inspector@latest --cli against the endpoint
   • Verify tools/list returns all 9 tools and tools/call executes successfully

Testing that has already taken place:

• PHPStan: No errors on MCPAdapterProvider.php and WooCommerceRestTransport.php
• Unit tests: 25 tests, 37 assertions — all pass
• PHP lint: Clean on all changed files
• API surface diff: Full comparison of v0.3.0 vs v0.5.0 public APIs — all WooCommerce-used classes/interfaces/methods are backward compatible
• Integration test: MCP initialize handshake returns valid response with protocol version 2025-11-25
• E2E test: Full CRUD cycle (products + orders) via MCP Inspector CLI — all operations succeed server-side
• Autoload verification: All MCP classes/interfaces load correctly in wp-env (including renamed Contracts namespace)

Milestone

• Automatically assign milestone for the next WooCommerce version

Changelog entry

• This Pull Request does not require a changelog entry. (Comment required below)