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

Annotations only cover readOnlyHint and idempotentHint; the description goes further by disclosing the key behavioral trait — that most huts return no availability and that stale/unrefreshable data is deliberately withheld, with a structured 'none' coverage, machine-readable reason, plain-language message and booking link. That is meaningful disclosure beyond the annotations, though nothing is said about latency or rate limits.

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?

Front-loaded with the core answer ('Free beds per night for one hut') and contained in essentially one dense sentence. The trailing clauses about coverage/reason/booking link are relevant rather than filler, though the sentence is heavy enough to be slightly hard to parse on first read.

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 carries the return-value burden and does so partially: it describes the failure shape (coverage 'none' + reason + message + booking link) but not the success shape (presumably free-bed counts per night). For a read-only, three-parameter tool this is close to complete, with the success payload left implicit.

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 100% and all three parameters (from, to, slug) are documented there with defaults and formats. The description adds no additional parameter meaning, so the 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?

Opens with a specific verb+resource+unit: 'Free beds per night for one hut', which an agent can immediately distinguish from get-hut (hut details) or search-huts (discovery). It does not explicitly name those siblings, so the differentiation is implicit rather than stated, but the scope is unambiguous.

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?

The description explains how to interpret a 'none' coverage answer ('which is a correct answer to pass on'), which is useful guidance, but it never says when to call this tool versus get-hut or search-huts, nor any prerequisite beyond the slug originating from search-huts (which lives in the schema). Usage is implied rather than directed.

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