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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered; the description adds what is actually in the payload (cast, dual critic/audience scores, metadata, representative embedded reviews) and the one-of constraint on inputs. It doesn't mention pagination depth or failure behavior for an invalid path, which keeps it off a 5.

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 doing distinct work: what you get, how to call it, and which sibling to prefer. The input constraint and the alternative are both front-loaded with no filler.

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 spelled out, and the description still previews the payload shape. Combined with the explicit input constraint and sibling routing, an agent has everything needed to select and invoke the tool 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 coverage is 100%, so the baseline is 3, but the description contributes a real constraint not present in the schema: both properties are optional with required=0, yet the tool demands 'exactly one' of path or URL. That mutual-exclusivity/discrimination rule is genuine added meaning; only the path format hint ('/m/...') slightly overlaps the schema's own descriptions.

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?

Opens with a specific verb and resource ('Fetch details for one Rotten Tomatoes movie') and enumerates the payload (cast, critic and audience scores, metadata, embedded audience reviews). It is immediately distinguishable from rottentomatoes_movie_reviews, which is named as the alternate for review rows.

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?

States the exact input contract ('Pass exactly one movie path (/m/...) or absolute movie URL') and explicitly routes the agent elsewhere: 'Use rottentomatoes_movie_reviews for a first-page sample of critic or audience review rows.' Both the when and the when-not are covered with a named alternative.

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