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

Annotations already declare readOnlyHint, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuine value by disclosing the return contents (availability status per title and deep links), which matters because there is no output 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?

Three short sentences, front-loaded with purpose, then return shape, then the key parameter hint. Nothing is redundant, though the second and third sentences could be tightened into one.

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?

With 10 parameters, no output schema and no explicit sibling routing, the description does well to cover the return payload but leaves filter semantics and pagination behavior unexplained. It is adequate, not complete, for a search tool of this surface area.

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 50% across 10 parameters; query, country, services, kids_mode and availability are already documented in the schema. The description only reinforces the country parameter's purpose, and says nothing about the undocumented filters (page, per_page, year_from, year_to, max_runtime_minutes) or how they compose.

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 names a specific verb and resource — 'Search the iWonder catalogue of documentaries' — and sketches the return shape (matching films, availability, deep links). It does not explicitly contrast with the siblings get_film and where_to_watch, so an agent must infer that this is the discovery entry point.

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 only usage instruction is 'Pass the viewer's two-letter country code to scope availability to their region,' which is parameter guidance rather than when-to-use guidance. There is no statement of when to choose this over get_film or where_to_watch, leaving that inference to the agent.

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