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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds genuine provenance context: results are recommendations published on the title's page rather than generated by search. It stops short of describing result count, ordering, or pagination behavior, but adds value beyond the 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?

Three tight sentences with zero filler. The core action and its scope lead; the disambiguation and sibling routing follow in descending order of importance.

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 no explanation, and annotations carry the read-only/open-world profile. The description covers the source of data, input constraint, and adjacent tools — nothing an agent needs to call it 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 coverage is 100% so baseline is 3, but the description adds two things the schema does not: the 'exactly one' mutual-exclusivity constraint between id and url, and the '(tt...)' id format hint. This meaningfully reduces the risk of passing both parameters.

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 (Fetch) and resource (IMDb's public 'More like this' title recommendations), scoped to 'exactly one title id (tt...) or title URL'. It explicitly distinguishes itself from a keyword search and names siblings (imdb_title, imdb_title_keywords), so an agent can tell it apart without opening schemas.

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?

Makes the key selection distinction explicit — these are page-published recommendations, 'rather than a keyword search' — and routes follow-up work to imdb_title and imdb_title_keywords. The alternatives named are more workflow continuations than competing choices, and there is no explicit when-not-to-use statement, but the disambiguation is clear.

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