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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=false and no destructiveness, so the safety profile is fully covered. The description adds real value by disclosing the shape of the content returned (categories plus their associated searcher terms), which is behavior no annotation conveys. With no output schema, however, it says nothing about result size, ordering, or format, so the disclosure stops short of full transparency.

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 with zero filler. The payload content is stated first and the routing advice follows, which is the correct front-loading for a zero-argument lookup tool.

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 no-parameter, closed-world listing tool with rich annotations and no output schema, the description covers what it returns and when to call it. The remaining gap is scale and format of the returned list, which an agent would want for planning, but that is a minor omission rather than a blocking one.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; the baseline of 4 applies. Schema coverage is reported at 100% and the empty object confirms no inputs are expected.

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 — the service categories navigi.ca uses — and adds that each carries the searcher terms it answers, which goes beyond the bare title. The only friction is terminological: the name says "needs" while the description says "service categories," so an agent must infer these are the same concept. Still clearly distinguishable from the sibling tools, which operate on services and communities rather than the category vocabulary.

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?

"Call this first when unsure which need word to use" is an explicit sequencing instruction that tells the agent when this tool precedes others. It implicitly routes the agent to find_services once the term is known, but never names that sibling or states when this tool should be skipped.

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