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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=false, so the safety profile is fully covered. The description contributes the ordering behavior (best-converting first), which is genuinely beyond the annotations, but says nothing about what metrics are included, whether the list is paginated, or how many widgets are returned.

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 compact sentences with the sort order front-loaded and the routing instruction second – good ordering. The opening phrase "The same numbers" is the one piece of wasted, ambiguous text, since it presumes unstated 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 burden of explaining the return shape falls on the description, and "the same numbers" does not tell the agent which metrics come back (conversions, views, conversion rate?). For a read-only analytics listing with one optional param this is workable but under-specified.

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?

There is a single optional parameter (project) with 100% schema description coverage; the schema explains it references list_projects and overrides the connection default. The description adds nothing about parameters, which is acceptable given the schema baseline, but also adds no value.

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?

"Per widget, best-converting first" identifies the resource and sort order, and the verb is implied by the tool name (list). However, "The same numbers" is a dangling reference to something the agent has no defined anchor for – presumably read_analytics, but that is never named – so what is actually being listed is only partly clear.

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?

Explicitly gives the triggering question ("which magnet is working") and names the alternative tool with the condition that selects it ("where one widget's traffic came from"). The alternative is referred to as "widget_results" rather than the actual sibling name read_widget_results, which is a small but real lookup cost.

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