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

Annotations already declare readOnlyHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description adds genuinely new behavior: the link lives ~15 minutes after the search, and on expiry a fresh search link at lastbilet.ru is returned instead — useful TTL and fallback semantics. It says nothing about auth or rate limits, hence not a 5.

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 with no filler, ordered purpose → lifetime/fallback → trigger, so the most decision-relevant facts come first.

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?

There is no output schema, and the description does explain what comes back (a link to the agency/airline site, or a fallback search link). Combined with the explicit call trigger and annotations, an agent has enough to invoke it, though the two required IDs remain unexplained.

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 must carry both parameters, and it does not. It only hints that offer_id/search_id derive from a 'выбранного варианта из search_flights', leaving the exact meaning and pairing of the two required IDs to inference.

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+resource: it returns a purchase link for the variant the user selected, and it names search_flights as the source of that variant, which separates it from siblings like cheapest_prices or price_calendar. An agent can tell what this tool produces without opening the 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?

The trigger is explicit: 'Вызывай, когда пользователь выбрал вариант' (call it once the user has picked an option). It also implicitly chains from search_flights, but it states no exclusions or what to do when the user has not yet selected, so it stops short of a full when/when-not/alternatives statement.

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