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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the safety profile is covered; the description adds the substantive value of what the response contains, including source URLs for every fact and future/roadmap assistants. There is no output schema, so this return-content disclosure is doing real work, though pagination/format details are absent (trivial for a single-object read).

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?

One front-loaded sentence led by the imperative 'Use this first', with no filler. The trailing enumeration is long but every item tells the agent something about scope, so it earns its length, if only just.

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 compensates by listing the returned content in detail, and annotations cover safety. The only minor omission is any mention of the locale parameter or output shape, which is low-stakes for a single-item descriptive read.

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 'locale' parameter is fully documented as an enum with only 'en'. The description says nothing about locale, so it adds no meaning beyond the schema — baseline 3 applies.

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+resource ('describe PolarJay') and enumerates exactly what the response covers (capabilities, measured assistants, languages, audience, operator, source URLs), which separates it from get_pricing / how_to_start / list_faq by content. It never names a sibling explicitly, 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?

'Use this first' gives a clear ordering cue that this is the entry-point tool for the product overview. It gives no explicit when-not condition or named alternative for the overlapping siblings (get_page, list_faq), leaving that to inference.

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