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

Annotations already cover the safety profile (readOnlyHint=true, idempotentHint=true, destructiveHint=false), lowering the bar. The description adds real behavioral value by requiring the agent to always return the page URL as an unchanged clickable link and explaining it is the only way to book or buy. No contradiction with annotations.

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?

Two compact sentences with no fill. The first sentence front-loads the tool's purpose and the full list of returned fields, while the second delivers the critical link-handling rule. Every clause earns its place.

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 read-only, two-parameter lookup with an output schema, the description is complete. It specifies what data the traveller receives and the essential delivery requirement about the URL. The schema plus output schema cover the remaining details, so nothing needed to call the tool correctly is missing.

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 lang and activity_key are already fully documented in the schema. The description only reinforces that activity_key selects a single activity, adding marginal semantic value beyond the schema. Baseline 3 is appropriate.

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: 'Details of one activity by activity_key' and enumerates the exact content returned (description, inclusions, duration, cancellation, dates/prices, photos, page url). This makes the tool's role immediately clear and distinguishable from search_activities and sibling get_* tools.

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 schema notes that activity_key comes from search_activities, which implies this tool is for retrieving details after a search. However, the description itself never explicitly says when to use this tool vs search_activities or other siblings, nor does it state exclusions. Usage is implied rather than clearly instructed.

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