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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds genuine behavioral context — that content is returned 'in the shop's own words' and precisely which topics are included — which tells the agent what kind of answer to expect and that it is authoritative shop copy rather than computed output.

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?

The scoping statement is front-loaded before the topic list, and every clause earns its place by naming a covered subject. The single long enumerated sentence is dense but readable; a short structural break before the usage rule would improve scanning.

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 two-optional-parameter read tool with no output schema, the description is nearly complete: the agent knows what to ask it for and what it will not cover. The one remaining gap is the return shape — whether facts come back as prose paragraphs or keyed fields — which would help an agent consume the result.

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 bucket and language are already fully documented, including their currency/locale effects. The description adds nothing about either parameter, which is acceptable at baseline but no better.

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 resource (variotrip's own-words shop facts) and enumerates exactly what is covered — data pool, trip length, delivery, payment, hotspot, activation, top-ups, support. That enumeration lets an agent distinguish it from price_grid and quote_route without opening any 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 closing clause 'Use for any question that is not a price' gives a clear positive rule plus an exclusion, routing non-pricing intent here and pricing intent to the price siblings. It never names a sibling tool explicitly, so the routing is inferred rather than spelled out.

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