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

Annotations already cover readOnly, idempotent, openWorld and non-destructive, so the 'read-only, runs straight away' line is largely a restatement. The genuinely additive part is the described return shape (id, id_base, sidebar, instance settings, parsed blocks for block widgets) and the named target site, which matter because there is no output schema.

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 verb, resource and ID format, then the workflow hint, then the return shape. The site parenthetical and 'Through Royally' clause are short and the whole thing is two dense sentences with no 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?

For a two-parameter, single-required-ID read tool with no output schema, the description covers identity, ID format, workflow position, target site and return shape. The only omission is error behavior for an unknown ID, which is minor for a low-complexity getter.

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, but the description adds value the schema lacks: concrete widget ID formats and the note that block widgets return parsed blocks. The site_id parameter is only echoed, not explained beyond the schema's own enum description.

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 (get one widget instance by ID) and pins the scope by contrasting it with wp_get_widgets ('shaped like one item of wp_get_widgets'). The concrete ID examples (text-2, block-3) make it unambiguous which tool to reach for versus the list tool.

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?

Gives an explicit sequencing rule ('Use it before wp_update_widget') and implicitly routes bulk listing to wp_get_widgets through the 'one item of' framing. It does not spell out a when-not condition (e.g. use wp_get_widgets when you don't know the ID), so it stops short of full routing guidance.

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