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

Annotations already cover the safe-read (readOnlyHint) and open-world profile, so the bar is lower, yet the description still adds real behavioral context: IMDb may return only an initial slice, so the caller should compare locations against total and check has_more. That is a genuine caveat not derivable from annotations or 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 sentences, each earning its place: purpose, input rule, then the completeness caveat and alternative. Front-loaded and free of redundancy.

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 an output schema present and annotations covering safety, the description supplies the remaining essentials: accepted inputs, the pagination/incompleteness warning, and the sibling alternative. 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 the baseline is 3, but the description adds the mutual-exclusion rule ('exactly one') and the tt.../URL format expectation, which the schema's two independent optional properties do not enforce. Modest but real value beyond 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 (Fetch) and resource (public IMDb filming-location rows and notes) scoped to a title, and explicitly names the sibling it is not (imdb_title_trivia for production facts). An agent can distinguish it from other imdb_title_* tools without opening a 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 exact input rule ('Pass exactly one title id (tt...) or title URL') and an explicit when-not/alternative directive ('Use imdb_title_trivia for production facts rather than locations'). Routing is unambiguous.

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