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

Adds real context beyond the annotations: cost model (no AI, no plan usage), non-destructive versioned save, and the return payload ('new slide URLs plus a preview'). Since annotations already declare readOnlyHint=false and destructiveHint=false, the description usefully explains why deletion ops are still non-destructive (a new version is saved). It does not describe failure modes or how layer/slide mismatches are handled.

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-loads the core action and cost in the first clause, then lists capabilities and the return value. It is a single long sentence with dense em-dash clauses — efficient but slightly harder to scan than a short structured list.

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 stating the return ('new slide URLs plus a preview'). It covers versioning (version_id default latest, a new version is saved) and the theme/layout/font knobs. Minor gaps remain around error behavior for invalid slide/layer references.

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 every parameter including the nested edit fields is already documented in the schema. The description's inline examples (op=hide with layer=number on slide 3, op=style with dx/dy/color) illustrate combinations but add little beyond the schema; the baseline of 3 applies.

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 ('Change an existing carousel layer by layer and re-render it') and scopes it to existing carousels, which separates it from the create/build siblings without needing their schemas. The enumerated operations (hide, set_text, set_photo, style, slide ops, theme/layout/fonts) make the surface area concrete.

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 selection signal — 'no AI, free (doesn't use the plan)' — which tells the agent this is the cheap path versus AI-generation siblings, and 'existing' implies the creation tools are for new carousels. It does not explicitly name an alternative tool or state when not to use it.

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