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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered; the description adds real context beyond that by disclosing the shape of the returned data and a conditional field (reviews_shown) that only appears for review widgets, including the edge case that 0 means an empty widget. It stops short of stating behavior on an unknown or foreign widget_id, which would have made it a 5.

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?

Two short sentences, zero filler, and the returned-field list is front-loaded. The second sentence is slightly elliptical ('A review widget has reviews_shown') but still parses correctly in context.

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?

There is no output schema, so the description must carry the return-value burden, and it does so by enumerating the fields returned plus one conditional field's semantics. For a one-parameter read tool this is close to complete; only error/not-found behavior is unaddressed.

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% and the single parameter widget_id is already documented in the schema as 'the id in list_widgets'. The description never mentions the parameter at all, so it adds no meaning beyond the structured field. Baseline 3 applies when the schema does all the work.

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?

The description states a specific resource ('One widget') and enumerates the payload it returns: settings, accounts, embed code, install status and the sites where it shows. That is enough to separate it from list_widgets or get_widget_stats by implication, but it never names a sibling or uses an explicit verb like 'retrieve', so differentiation is inferred rather than stated.

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?

Usage is only implied: an agent can deduce this is the detail-fetch for a single widget, but there is no when-to-use framing, no pointer to get_widget_stats/preview_widget for other needs, and no note that a widget_id must come from list_widgets (that lives in the schema instead). Adequate but with clear gaps.

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