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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds genuinely new behavior: fees are already included in the total, no inventory is reserved, no payment is taken, and website_url arrives with dates and guests pre-filled — all decision-relevant for an agent that might otherwise assume a booking side effect.

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, front-loaded with what is read, then inputs, then pricing semantics, then the no-commitment disclaimer, then the handoff. Nothing is repeated and every sentence carries information an agent needs.

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 no explanation, and the description covers the read-only nature, the estimate inputs, and the next step. The only shortfall is the undocumented locale parameter and slug expectations, a minor gap for a five-parameter tool.

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 only 40%, so the description must carry weight, and it does clarify that both dates plus guest count are jointly required to produce an estimate. Still, it says nothing about locale (en/sv), the listing_slug format, or why the two dates are coupled — the date-limit constraints live only in the schema property descriptions.

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 uses a specific verb ('Read') with concrete resources: a public Guestit listing, house rules, cancellation policy, and a dated price estimate. It is clearly a single-listing detail lookup rather than a search, though it never names search_stays, compare_stays, or resolve_destination to draw the boundary 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?

It states a usage condition for pricing ('Supply both dates and the guest count for an estimate') and a follow-on action ('Open website_url to continue on Guestit'), which implies the tool's role in a booking flow. However, it never says when to prefer it over search_stays or compare_stays, so the agent must infer the routing from the sibling names alone.

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