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

Annotations already declare destructiveHint=true and openWorldHint=false; the description adds genuinely new behavior: partial-update semantics (unspecified fields are preserved) and the propagation surface ("Shows in the editor, Preview and the export"). It stops short of saying what a destructive overwrite means here (e.g. whether passing a new effect replaces prior per-scope settings), which keeps it out of the top band.

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 compact sentences, front-loaded with the core action, then the value vocabulary, then the mutation semantics and visibility scope. Dense but every clause carries information; no filler or hedging.

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 4-parameter mutation with no output schema, the description plus annotations cover what the agent needs: what changes, that changes are partial, and where they surface. A default value or reset behavior (e.g. type "none") would close the remaining gap.

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 0%, so the description has to carry parameter meaning — and it largely does, mapping each enum value to its parameter (effect: none/fadeIn/slideIn/scaleIn/popIn; sectionScope: all or hero; elementScope: all, images, or headings). Only projectId goes unmentioned (self-evident), and "headings" is a small mismatch with the schema's singular "heading".

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 and resource ("Set how the site animates in") and grounds it in a familiar analogy (the editor's Animation panel). It then enumerates the exact vocabulary the tool operates on (effect, section scope, element scope), so the agent knows precisely what this tool controls and can distinguish it from the many other uichemy_set_* modifiers.

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?

The description makes clear when this applies — site entrance animation, applied to all sections or the hero, and to all elements, images, or headings — and the semantics of partial application ("Only the fields passed change") tell the agent it can tune one axis at a time. There are no explicit exclusions or named alternatives, but no sibling tool covers animation, so the ambiguity is low.

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