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

Annotations already declare readOnlyHint, idempotentHint and non-destructive behavior, so the safety profile is covered. The description adds genuinely new behavioral context: the offer_id has a hard 30-minute TTL after the originating search. It omits what the API returns for an expired id, but for an annotated read tool this is solid.

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?

Two sentences, front-loaded with the identity and payload of the resource, followed by the one operational constraint. No filler or restated boilerplate.

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 spelled out (though the description helpfully previews them), and annotations carry the safety profile. The remaining gap is error/TTL-expiry behavior, but the definition is otherwise sufficient for correct invocation.

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 100% and the single parameter is fully documented, so the schema does the heavy lifting — baseline 3. The description's only added nuance is that the id must come from a recent search, which overlaps with the 30-minute TTL statement rather than expanding on the parameter itself.

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 (gets/returns) and resource (one fare/offer by offer_id) and enumerates what comes back: per-person price, flights, booking link, validity window. The phrase 'from a recent flight search' cleanly separates it from egf_search_flights and the prepare_* siblings.

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 supplies a concrete usage window — 'Works for 30 minutes after the search' — which tells the agent exactly when this tool is callable. It stops short of naming an alternative for expired/absent offer_ids or pointing at egf_prepare_flight_offer for new offers.

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