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

Annotations already cover readOnly, openWorld, idempotent and destructive=false, so the safety profile is free. The description goes beyond them by disclosing the affiliate/commission relationship on booking_url and warning that Viator confirms final price, availability and cancellation terms before payment, which is real behavioral context an agent needs. It omits rate limits or pagination behavior.

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?

Front-loads the read-only marker and purpose, then layers return fields, date semantics, sort default and the affiliate disclosure in a logical order. It is dense but each sentence carries information; only the return-field enumeration slightly overlaps with the output schema.

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 the description need not detail return values, yet it still summarizes them usefully. For a zero-required-parameter search tool the guidance is nearly sufficient; the only gap is no routing hint toward the sibling listing/category/filter tools.

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% across 10 parameters, so the description is expected to compensate. It does explain the date-range semantics and the sort default ordering, but page, limit, currency, max_price, min_rating and free_cancellation are left with no added meaning beyond their self-evident names, leaving the compensation partial.

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 and resource ('Live search of bookable tours and activities') plus a precise geographic and source scope (Boston, MA from Viator's partner API). It does not explicitly differentiate from the sibling search_listings, so an agent cannot tell from the text alone when this beats the generic listing search.

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 description explains the default sort behavior and that start_date/end_date restrict results to products Viator lists as available, which implies when the date filters matter. However, it never names an alternative (search_listings, list_filters) or states when-not to use this tool, leaving selection between siblings to inference.

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