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

Despite annotations already declaring readOnlyHint, the description adds substantial behavioral context: server-side registry read, verification that every returned key exists, invented names dropped and surfaced under dropped_not_in_registry, and a credit cost versus a free sibling. It also warns keys are non-obvious (text_align, end), which shapes how an agent interprets results.

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 the core question and answer shape, and most sentences carry decision-relevant information (cost, verification, non-obvious naming). It is slightly long and rhetorically framed, but no sentence is pure filler.

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?

No output schema exists, so the description carries the return-value burden and does: 2-3 verified keys plus a dropped_not_in_registry list. Combined with cost and verification semantics, an agent has everything needed to call and interpret it.

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 description coverage is 100%, so the baseline is 3. The description still adds meaning by explaining that a widget registry can exceed a thousand controls with responsive variants and that 'container' is passed for sections — context the schema alone hints at but does not convey in terms of scale and cost.

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 precise verb+resource ('give a widget and what you want to change; get back the 2-3 REAL control keys') and explicitly distinguishes itself from the sibling wp_widget_controls by framing this as an answer rather than a catalogue. An agent can tell the two apart without opening either schema.

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?

Names the alternative (wp_widget_controls) and the exact condition that selects this tool over it ('when you want an answer rather than a catalogue'), plus the cost trade-off. When-to-use is fully specified.

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