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

Annotations already declare readOnlyHint, destructiveHint=false, and openWorldHint=false, so safety is covered. The description adds substantial behavioral context by listing the exact return values (delays, total time, step used, CSS snippet for linear patterns) and warnings about steps under one frame and very long lists.

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?

A single dense paragraph, front-loaded with the core purpose. Every clause contributes information about parameters, outputs, or warnings, with no filler. Slightly harder to scan than a bulleted list but still efficient.

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?

No output schema exists, so the description must carry return-value information — it does so completely, enumerating outputs and warnings. Combined with full schema coverage for inputs, an agent has everything needed to call the tool correctly.

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%, so baseline is 3. The description adds value by supplying the default for duration_ms (300) that the schema omits, and by characterizing budget_ms as 'a convention' with its default. It also reinforces the count range and pattern options.

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 — 'Plan staggered reveals' — and details exactly what inputs it takes and what outputs it returns. It is clearly distinct from sibling tools like design_easing or plan_durations, though it does not explicitly name those alternatives.

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 purpose implies when to use it (planning staggered animations), but there is no explicit guidance on when to choose it over related tools such as design_easing or plan_durations, nor any exclusions. Usage is inferable but not spelled out.

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