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

Annotations already declare read-only, idempotent, non-destructive behavior, so the safety profile is covered. The description adds genuinely useful context beyond that: the no-API-key degradation mode (max 20 results, cached prices only), the rule that a price only appears with both dates, and that it is the all-inclusive total. It does not mention pagination or caching behavior of live rates beyond the 30-45s note in the schema.

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-loaded with the core capability and preconditions, then constraints and the sibling routing. Dense but every sentence carries information; the parentheticals about pricing and the API key could be tightened slightly.

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?

For a 17-parameter search tool with no output schema, the description covers search modes, return contents (ratings, location, amenities, images, review insights), pricing conditions, and the free-tier limitation. What it lacks is guidance on how the many optional filters interact (e.g. budget vs. include_rates), but the essentials for correct invocation are present.

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%, so every parameter is already documented in the schema, making 3 the baseline. The description adds only the cross-parameter rule that prices require both check_in and check_out, which the schema also states per-field, so incremental value is limited.

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 ('Search the VistaLink hotel catalogue') plus its scope (one city or around a point). It also names the sibling to use for open-ended questions (chat_about_hotels), so the agent can distinguish it from siblings without opening schemas.

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?

Gives explicit preconditions ('Needs city, latitude+longitude, or hotel_name') and an explicit alternative for a different intent ('For open-ended questions use chat_about_hotels'). It also states the condition under which prices are returned, which governs how the agent should call it.

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