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

Annotations already declare readOnlyHint/openWorldHint/destructiveHint=false, so the safety profile is covered. The description adds value beyond that by disclosing the return shape (decal ids, pixel dimensions, preview URLs, plus metadata fields) even though no output schema exists, and by explaining how ids are consumed downstream.

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?

Front-loaded with the return contents, then a single usage sentence — every clause earns its place and nothing is redundant. It is dense in the first sentence but not padded.

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 no output schema, the description carries the return-value burden and does so well, listing the artwork kinds and accompanying metadata. For a two-parameter read tool with annotations covering safety, this is essentially complete; only a note on result volume/pagination is absent.

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 only 50%: the 'id' param is documented as 'TMDB id from search_content', which the description reinforces, while 'type' relies solely on its movie/tv enum. The description's 'A movie or TV title's own artwork' implicitly frames the type parameter, adding modest meaning over 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?

The description names a specific verb+resource (fetch a movie/TV title's artwork) and enumerates exactly what comes back: posters, wordmark logos, backdrops as decal ids with pixel size, preview URLs, plus title/year/tagline/overview. It is clearly distinguishable from the sibling search_content, which the description explicitly positions as the id source.

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 states the prerequisite and source ('Ids come from search_content') and tells the agent what to do with the result ('Place one with decals[].id in the same intent as the content... sized by width like any decal'). There is no explicit when-not-to-use exclusion, but the workflow context is unambiguous.

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