At some point after you’ve registered your first ability and stood up an MCP server,
something will not work the way the docs implied it should. wp_register_ability()
will return null with no visible explanation. A tool that worked in one MCP client
will silently vanish from another. An ability with no parameters will validate fine
in one place and fail with a cryptic schema error in another. None of this means the
Abilities API or the MCP Adapter is broken, it means you’ve hit one of a small, known
set of real, documented failure modes, and this course exists to give you the
workflow and the specific fixes for each one.
This is not a conceptual course. Every lesson here traces back to a real, closed
GitHub issue against the WordPress/mcp-adapter repository, cited by number, with the
actual root cause and the actual resolution the project’s maintainers and community
landed on, not a guess at what plausibly could have gone wrong. You’ll build a
repeatable diagnostic workflow (reproduce, check the log, inspect with a real tool,
isolate the failing layer), then walk through the specific errors that workflow keeps
turning up in practice: wp_register_ability() returning null, a WooCommerce
registry conflict that turned out not to be what it looked like, hook-timing and
load-order mistakes, and two distinct, separately-fixed bugs around empty
input_schema objects. The last two lessons cover the tools that make all of this
faster to diagnose: the official MCP Inspector, and the adapter’s own error handler
and observability extension points.
This course assumes you’ve registered at least one ability and built a working MCP server already, and that you’ve hit something that didn’t behave as expected. If you haven’t reached that point yet, start with WordPress AI Foundations (Course 1) for the Abilities API itself, then Build a WordPress MCP Server From Scratch (Course 2) to get a real server running. Come back here the first time one of your abilities doesn’t register, doesn’t validate, or doesn’t show up where you expected it to.