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

Annotations already declare readOnly/non-destructive, and the description adds real behavioral context: ordering (brand's own first, then built-ins), the needs-vs-takes slot contract, that layouts adapt to every size, auto-fit text, brand color/face/logo application, and self-filling logo. It stops short of describing output shape, but for a read-only list tool this is rich.

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 what the tool returns and the needs/takes distinction, then a scannable enumeration of layout families. Dense but every clause adds information; the long single paragraph is slightly heavy but 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?

No output schema exists, so the description must carry return-value burden, and it does explain what each layout entry conveys (when to use, needs, takes) and the adaptive behavior. The layout-family list is illustrative rather than exhaustive, which is a minor gap.

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% for the single workspace parameter, so the schema already carries the semantics. The description adds nothing about the workspace argument, so baseline 3 is appropriate.

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 ('lists the slide layouts napkin_deck_compose can build from') and clarifies scope (brand kit first, then built-in). It is clearly distinguishable from siblings like napkin_deck_compose or napkin_slide_add, which consume rather than enumerate layouts.

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 explicit selection guidance ('Pick by what the slide has to say') with a concrete mapping of content type to layout family. It implies this is a lookup step before composing, though it never explicitly states when NOT to call it or names an alternative.

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