Get movies in or coming to cinemas

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

Annotations already cover read-only/open-world, but the description adds substantial non-obvious behavior: region changes the actual movie set rather than re-sorting, an unrecognized code like 'ZZ' yields an empty page while 'XX' is a real pseudo-region, release_date is the country's date and may predate the window for re-releases, and ordering is popularity-based, not chronological.

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 purpose and alternatives, then the caveats; every clause carries information and nothing is filler. It is nonetheless a single dense paragraph whose nested parentheticals make it harder to scan than a short bulleted structure would.

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 four-parameter list tool with an output schema, everything an agent needs is present: mode selection, regional filtering semantics, window derivation and its approximate bounds, and result ordering. Nothing material is deferred to the schema or left to inference.

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 coverage is 100%, so the baseline is 3; the description still adds real meaning for `region` (per-country result sets, invalid-code behavior, the 'XX' pseudo-region) that the schema's one-line 'ISO-3166-1 country code' does not convey. It also documents where the implicit date window comes from and that it is returned as `dates` {minimum, maximum} with approximate spans per list, though page/language are left entirely to the schema.

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 ('List movies in cinemas now ... or opening soon ... in one country') and binds each mode to a concrete parameter value. It explicitly distinguishes itself from get_trending and discover_movies, so an agent can route correctly without reading 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 the triggering user intents ('what's playing in theaters', 'what comes out next month') and names two alternatives with the condition that selects each: get_trending for popularity regardless of release, discover_movies for an arbitrary date range.

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