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

Annotations already declare readOnly/idempotent/non-destructive, and the description goes well beyond that by disclosing result ordering (newest first) and a data-scope exclusion (only public previews, the paid full guide is never included). Since there is no output schema, enumerating the returned fields is genuinely additive rather than redundant.

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 tightly packed sentences with the routing instruction front-loaded ahead of the field inventory. Every clause carries distinct information (purpose, alternative tool, returned fields, ordering/scope) and none restates the name or annotations.

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 adequately covers return contents, ordering, and visibility limits, and the schema covers both inputs. The one gap is pagination behavior: nothing explains how to retrieve results beyond the limit or whether a cursor exists, which matters for a 50-item-max listing.

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 both parameters (limit, country) are already documented with ranges, defaults, matching rules, and examples in the schema. The description adds no additional syntax, default, or matching nuance beyond what the schema provides, so the baseline of 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?

States a specific verb+resource (browse published Fly Frugal itineraries) and immediately scopes it as a discovery/listing operation rather than a detail fetch. It explicitly names the sibling get_itinerary and the handoff condition (pass a returned slug), so an agent can distinguish the two without opening either 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?

"Use this to discover which destinations have a guide, then call get_itinerary with a returned slug for one guide's preview" gives an explicit when-to-use and names the alternative tool with the exact linkage value. The workflow (list first, then fetch by slug) is fully specified, leaving nothing to inference.

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