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

Annotations already declare readOnly/idempotent/closed-world, and the description adds real context beyond them: the approved-account requirement, the OAuth sign-in flow, a setup URL, and the exact shape of returned metadata including per-kind creatability reasons. That is exactly the value-add the description should provide on top of structured hints.

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?

Auth requirements are front-loaded and the return-shape sentence is dense but informative. It runs long for a zero-parameter list tool, with billing/tile-slot detail that is close to the edge of what earns its place, but every clause carries actionable information.

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, and the description compensates by describing the returned metadata fields and the tileInputs structure. Auth setup, creatability semantics, and the hand-off to plan_overlay_pack are all covered, so an agent can call it and use the result without guessing.

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?

With zero parameters and 100% schema coverage there is nothing for the description to disambiguate, so it meets the baseline. It usefully clarifies that tileTexts is passed to plan_overlay_pack, not to this tool, preventing a parameter mix-up.

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 ('List every animated-overlay scene kind') and enumerates the metadata returned (label, animates, cam-frame, creatable, reason). It explicitly positions itself as the single source of truth for kind names, which separates it from sibling creation/planning tools.

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 a clear directive ('never assume or hardcode a kind name') and routes the agent forward by naming plan_overlay_pack and the tileTexts override for sheet-pack kinds. Lacks an explicit 'when not to use' or prerequisite ordering against siblings like list_overlay_projects, but the usage context is clear.

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