Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Goes well past the annotations: explains that settings is null and settings_editable is false for legacy widget types without a REST representation, that rendered is an empty string while the widget sits in wp_inactive_widgets, and that the call is refused on block themes. Annotations only cover the safety profile; this adds the actual output semantics and failure mode.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with purpose and the required parameter, and nearly every clause carries actionable information. It runs long as a single block, and the closing sentence about Royally's read-only marking could be trimmed without losing meaning.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description supplies the full return shape ({ id, id_base, sidebar, settings_editable, settings, rendered }) and explains the two fields whose values are non-obvious. Nothing an agent needs to call this and interpret the result is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% so the baseline is 3, and the description still adds value by giving concrete id formats ("block-3", "text-2", "recent-posts-4") and stating the id_base plus instance-number structure, which the schema only gestures at. It also flags that settings is the object wp_update_widget accepts as instance, linking the two tools.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ("Gets one widget by id") plus the payload it returns (settings and rendered HTML preview). That single-widget framing cleanly separates it from the sibling list tools wp_list_widgets and wp_list_sidebars.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Tells the agent where widget_id comes from (wp_list_widgets or wp_list_sidebars) and names an explicit alternative for the unsupported case: refused on block themes, use wp_list_templates instead. It also states the required capability and the Royally read-only routing.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.