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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered and the description does not contradict it. The description adds the 'on sale' semantic and output fields, but no additional behavioral traits such as pagination, ordering, or filtering behavior, keeping it at baseline.

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?

One compact sentence front-loads the core concept ('The city guides on sale') and then enumerates the returned fields. There is no filler, repetition of annotations, or unnecessary detail.

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?

Given the empty parameter schema, read-only annotations, and presence of an output schema, the description is sufficient for basic invocation and understanding of what the tool returns. It could be slightly more explicit about whether this is the complete set of guides or whether any selection behavior applies, but the tool is simple enough that this is a minor gap.

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?

The tool has zero parameters and schema description coverage is effectively 100%, so the baseline for parameter semantics is 4. The description's field list concerns output, not parameters, so there is nothing extra needed here.

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?

The description identifies the resource ('city guides') and the specific data returned (city, standfirst, price, buy URL), so an agent can tell this is a listing tool for guides. It does not include an explicit verb like 'list' or 'return' in the description itself, and it does not explicitly contrast with sibling tools, so it falls just short of the top score.

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 phrase 'on sale' implies the use case: an agent needing purchasable city guides with price and buy URL. However, the description does not name alternatives or explain when to prefer list_guides over get_guide, list_articles, or list_destinations, so the guidance remains implicit.

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