setAspectRatio

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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful behavioral context beyond that: 'Annotations on the frame keep their place and shape,' disclosing that existing overlay content is preserved when the ratio changes. It stops short of stating whether the change is immediate or undoable.

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-loads the core action, then packs value-mapping and sibling equivalence into two tight sentences. The enumeration is long but every entry carries decision-relevant information for picking a ratio.

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 2-param, no-output-schema mutation tool with annotations covering safety, the description covers purpose, valid inputs, cross-tool equivalence, and preservation behavior. Minor gaps remain (immediacy of effect, undo, permission requirements) but nothing blocks correct invocation.

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 meaning beyond the schema by explaining what each ratio value is for (16:9 = X/YouTube/slide, auto = follow recording) and by clarifying that a token from getCurrentDocument's settingsContext.originalAspectRatios is a valid input.

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+resource ('Set the shape of the exported video') and enumerates the value space, so the agent immediately knows this is an aspect-ratio setter. It also explicitly relates itself to the sibling setEditorSettings ('The same as setEditorSettings with aspectRatio alone'), disambiguating it from that tool.

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 concrete usage guidance by mapping each value to an intent (16:9 for X/YouTube/slide, 9:16 for vertical story/short, 1:1 or 4:5 for square feed, auto to follow the recording). Lacks explicit when-not-to-use guidance, but the setEditorSettings equivalence tells the agent the two can be used interchangeably.

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