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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so safety needs no restating. The description adds real behavioral detail beyond them: result cardinality is capped at one, only destinations with Guestit stays are returned, and the empty-result path requires asking the user about a nearby larger place. It stops short of saying whether a fuzzy/partial match is attempted, which is the one behavior an agent would still wonder about.

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?

Four short sentences, zero filler, and the ordering is correct: what it does, then how to call it, then what comes back, then what to do when it fails. Each sentence carries a distinct instruction.

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?

An output schema exists, so return structure needn't be explained, and the description still volunteers the useful cardinality fact (at most one). Combined with the fallback guidance this is nearly complete; the only gap is the unmentioned `locale` parameter and what a non-matching vs. ambiguous result looks like.

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 description coverage is 0%, so the description carries the full burden. It does clarify the meaning of `query` (a bare place name like 'Åre' or 'Stockholm', not a hotel or a country), but `locale` with its en/sv enum is never mentioned, leaving one of two parameters documented only by its schema. That partial compensation lands at the baseline.

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 and resource ('Find the Guestit destination') and pins down scope: resolves a place name, returns at most one place, only places with Guestit stays. The phrase 'before searching stays' positions it as a prerequisite step relative to search_stays, so an agent can distinguish it from its siblings without opening a schema.

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?

Gives clear when-to-use ('before searching stays') plus a concrete input rule ('Pass the place alone, such as Åre or Stockholm') and explicit failure handling ('ask the user about a larger place nearby'). No sibling tool is named as an alternative and there is no explicit when-not-to-use, so it falls short of a 5.

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