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

Annotations cover safety (readOnlyHint=false, idempotent, non-destructive), and the description adds real behavioral context beyond them: explicit values override site-derived values, and producing a site pulls colours/fonts/logo plus page screenshots into shots that show a screen. It never explains error behavior for invalid fonts/colours, which is the main remaining gap.

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?

It is short (~55 words), but it is written as sentence fragments with an unclear pronoun ('With site, they are read…'), and the important partial-update constraint is not front-loaded as a verb-led statement. Some restructuring would make it easier to parse quickly.

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?

For a 7-parameter setter with full schema coverage and safety annotations, the description covers the key behavioral surprises (partial update, site-derived brand). It omits what the call returns and how failures (bad hex, unknown font) surface, leaving an agent to infer the outcome.

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 heavy lifting is done by the schema; the description only adds the precedence rule (explicit params win over `site`) and a practical constraint that ink must read on bg. That is useful but modest, so the baseline 3 is right.

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 lists the brand fields (name, colours, fonts, corner radius, logo) of 'the whole film', which makes the resource clear, but it never states a verb — the reader must infer 'set' from the name/title. It also never contrasts itself with siblings like rename_film or edit_film that touch overlapping attributes.

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?

'Only what is given changes' conveys the partial-update pattern, and 'Make sure the text colour reads on the background (check_film measures it)' routes the agent to a verification sibling. However, there is no explicit when-not-to-use guidance and no mention of rename_film as the alternative for renaming only.

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