Fill content and animate in one call

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

Annotations indicate mutability but no destructiveness. The description adds atomicity and the specific benefit of avoiding flash, plus the return structure. It does not contradict annotations and adds meaningful behavioral context beyond what annotations provide.

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?

The description is very concise: two sentences and an argument list. It front-loads the core purpose and eliminates unnecessary words. Every sentence adds value.

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?

Given the tool's complexity (7 params, nested object) and no output schema, the description covers the return value and the core atomicity benefit. It could include more on error handling or idempotency, but the essential context is present.

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 parameters are already well-documented. The description lists argument groups but does not add significant new meaning beyond the schema. It provides some context for payload and state but mostly restates schema info.

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 clearly states the tool performs an atomic set of payload and animation state to avoid flash, distinguishing it from separate fill-then-animate sequences. It uses a specific verb-resource combination and references sibling tools implicitly.

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 explains when to use the tool (to avoid stale content flash) and contrasts with a separate fill-then-animate approach. However, it does not explicitly list when not to use it or mention alternatives by name, though sibling tools exist.

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