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

Annotations already declare readOnly, openWorld, idempotent, and non-destructive behavior. The description adds valuable context by explaining that unranked titles return empty and that this means 'not in either list' rather than 'does not exist', which aligns with and reinforces the openWorldHint.

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 sentences, each earning its place: one for the core purpose, one for usage triggers, and one for the empty-result caveat. The most important information is front-loaded.

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 simple one-parameter lookup tool with no output schema, the description covers purpose, usage, and an important edge-case interpretation. It does not specify the exact output shape, but 'side by side' sufficiently implies the rank comparison.

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 schema fully documents the single required 'query' parameter with an example ('godfather'). The description does not add additional parameter meaning beyond referring to a film title, so the schema carries the load and a baseline score of 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?

The description clearly states the resource: a film's rank in both the IMDb Top 250 and Letterboxd Top 500, shown side by side. It differentiates this tool from general ratings or search tools by focusing on list membership and rank.

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?

It explicitly says to use this for 'what rank is X' or 'is X in the top 250' questions, which gives concrete triggers. It also sets a boundary by saying only ranked films are covered, though it does not name alternative sibling tools for unranked or non-existent titles.

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