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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered without prose. The description adds the return shape (ids only) which is genuinely helpful for chaining. It says nothing about matching semantics (substring vs AND/OR across the listed facets), result cap, or ordering — real behavioral gaps for a search tool.

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, with the search scope front-loaded and the return value trailing. Every clause earns its place.

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 one-parameter tool with a full schema, complete annotations, and no output schema, the description covers the main thing an agent needs beyond structured fields: that the result is ids destined for fetch. Only the multi-keyword combination rule and any result limit are left unstated.

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 already carries a concrete example (世田谷 英語 / 豊洲小). The description adds no meaning beyond that — it does not say whether multiple keywords are ANDed or ORed, which is the one thing an agent actually needs to know here. Baseline 3 is correct.

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 (search) plus the exact searchable facets — facility names, areas, wards, operators, tags, pickup schools — and what comes back (ids). That is materially more than the name/title. It does not, however, distinguish itself from the sibling search_facilities, which an agent will have to disambiguate on its own.

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?

"Returns ids for fetch" implies the intended two-step workflow: search here, then call fetch with the ids. That is useful implied guidance, but there is no explicit when-to-use versus search_facilities/get_facility, and no statement of when this tool is the wrong choice.

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