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 and the bar is lower. The description's remaining content (returned image fields) overlaps with the output schema rather than adding behavior, and it says nothing about pagination behavior, ordering, or what an empty result means.

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?

Two tight sentences with no filler: the resource and payload are stated first, the filtering instruction second. Every clause earns its place.

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, the description need not explain return values, and the 100%-covered input schema documents all four parameters, so the definition is nearly self-sufficient. The gap is guidance on id vs url selection (zero required params means the agent must infer which identifier form to supply).

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 description coverage is 100% and every parameter is documented inline, including the full list of type values and the limit default/max, so baseline 3 applies. The description adds little parameter meaning beyond that, and its advice to call imdb_image_types for accepted values is partly redundant since the schema already enumerates them.

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 names the resource precisely ('IMDb name media index: image metadata') and enumerates what each row carries (original URL, dimensions, caption, credited people), so an agent knows this returns image records for a person rather than for a title. It lacks an explicit verb and never contrasts itself with the close sibling imdb_title_images, so it falls just short of a 5.

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?

'Filter with type; call imdb_image_types for the accepted values' gives concrete routing for the filter dimension and points at the sibling that enumerates legal values. It does not say when to prefer this over imdb_name_videos or imdb_title_images, and offers no exclusions, so it stops at clear context without full when/when-not guidance.

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