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

Annotations already declare readOnlyHint and openWorldHint, but the description adds real behavior beyond them: upstream endpoint gating explains why certain fields are absent, and 'an unknown id fails with not found' gives the failure mode. It does not cover output shape or any rate/limit behavior, so it falls short of a 5, but the added context is substantive.

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 action and field list, then limits, then the search alternative — good ordering with no filler sentences. Slight redundancy in restating that activity_id is required, which the schema already enforces, keeps it off a 5.

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 return values need not be explained, yet the description still summarizes the card surface while adding the gating rationale and the not-found failure mode. For a one-parameter read tool this is fully sufficient to call correctly.

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% and the single parameter is already documented as 'Klook activity id, as returned by /klook/search'. The description's provenance note largely restates that, adding little new meaning — baseline 3 applies when the schema does the heavy lifting.

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 ('Get one Klook activity's public card-level record by activity_id') and enumerates the returned fields (title, URL, city/country ids, price strings, rating, review count, sold-out state, image, type, coordinates, tags). It also explicitly scopes itself as 'Klook's card surface, not the full detail page', which separates it from detail-page siblings without the agent 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?

Gives both the when ('activity_id is required and comes from a klook_search result') and the alternative ('Use klook_search to list many activities in a destination or category first'). It also sets an expectation boundary — descriptions, itineraries, inclusions, availability and per-activity reviews are explicitly not obtainable here — so the agent knows not to retry for those.

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