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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower, yet the description still adds non-obvious context: results retain missing or unavailable listings rather than erroring, and prices include fees but do not hold inventory or create a booking. That is genuine behavioral value beyond the annotations.

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?

Three short sentences, zero filler, with the core purpose and the cardinality limit front-loaded before the caveats about missing listings and pricing.

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 values need not be described, and the key caveats (unavailable listings retained, prices not bookable) are covered. The main remaining gap is not routing the agent from search_stays into this tool by name.

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 only 40%, and the description compensates only partially: it reinforces the 2-4 slug bound and the shared date/guest constraint, but says nothing about the locale enum or the 730-day check-in/night limits that the schema documents for the dates.

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 (compare) over a specific resource (Guestit listings) and bounds the scope with 'two to four distinct' listings for shared dates and guest count. This visibly separates it from search_stays and stay_details, though it never names those siblings explicitly.

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 'two to four distinct listings' constraint implies the caller must already hold listing slugs (i.e. use this after a search), but that sequencing is left to inference. No explicit when-to-use/when-not-to-use statement or named alternative is provided.

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