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

Beyond the annotations, the description discloses that the tool saves the clip but performs no render, that moments return 'as it was' with the moment:<id> handle, and that list=true lists rather than mutates. These are real behavioral facts an agent could not infer from readOnlyHint=false / destructiveHint=false.

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?

It is front-loaded with the when-to-use condition and the core undo semantics follow the dense parameter rules. It is slightly long and run-on with parentheticals, but nearly every clause carries operational meaning and nothing is padding.

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 4-parameter mutation tool, the description covers triggers, ordering, defaults, limits, the special moment case, and the save-vs-render side effect. With an output schema present, it does not need to explain return values, so an agent has everything required to call it 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 coverage is only 25%, so the description carries the load: it defines the default behavior with no edit_id/count, the meaning of count (newest n, up to 10), the semantics of edit_id (undo back to and including), and list=true. That fully compensates for the undocumented parameters and even supplies the moment:<id> format.

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 names a specific verb and resource ('take back changes you made to a clip with the edit tools') and pins down the ordering model ('newest first, the same as Undo in the Slice editor'). It also covers an edge case (restoring a removed storyboard moment), which is exactly what separates it from siblings like set_trim or set_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?

It gives an explicit trigger ('Use this when the person wants to take back changes...') and clarifies that list=true is a read-only listing mode rather than an undo. It doesn't name a sibling to use when the intent is to redo or inspect history, but the positive guidance is clear.

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