Cels

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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the safety profile is covered. The description adds genuinely useful behavior beyond that: tween/oscillate operate 'in one transaction' and 'fill in any missing in-between cels from the start cel,' disclosing atomicity and side effects. It stops short of stating reversibility or permission needs.

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-loaded with purpose followed by the op list, then targeted explanations of the less obvious operations. Dense but nearly every sentence carries information an agent needs to disambiguate ops. Slightly long, though not padded.

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 20-parameter, 11-operation tool with an output schema present, return values need not be explained. The description covers the op semantics and transaction behavior well, but leaves a few parameter interactions (sprite selection, toLayer/toFrame pairing) to the schema.

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 70%, so the schema does much of the work, but the description adds real semantic value by mapping operations to intent (move vs link vs tween vs oscillate) and clarifying the opacity/position distinction for tween. It does not document every parameter (e.g. sprite, toLayer, frames) but complements the schema well.

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 and defines the concept precisely: 'Manage cels — one layer's image on one frame.' It then enumerates all 11 supported operations, so an agent immediately knows the tool's exact scope. It is clearly distinguishable from siblings like layer or frame.

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?

Explains what several operations mean and implicitly when to prefer them: 'move' for shifting a limb without redrawing, 'link' for sharing an image across frames, 'tween'/'oscillate' for procedural in-betweens. It gives clear operational context but never explicitly routes the agent away from alternative sibling tools (layer, frame).

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