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

Annotations already cover safety (readOnlyHint, idempotentHint, destructiveHint=false), so the 'Read-only' sentence is largely redundant. However, the description adds genuine behavioral context beyond the annotations: main/mobile edits do not implicitly propagate to independent phone formats, and the response carries an editor link and an editing read receipt.

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?

Three tight sentences, payload-first, with the propagation caveat placed where it matters. The trailing 'Read-only.' is redundant with annotations but costs only one clause.

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?

An output schema exists, so the description needn't detail return values, and it still usefully names the notable ones. The remaining gap is that the editing workflow (omitting language lists translations only; re-call before transform_layout) is only discoverable in the schema, not the description.

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?

No parameter is named or explained in the description; only 'one variant and language' hints at variantId and language. With 60% schema description coverage the schema does most of the work (language and generationId are well documented), so this lands at the baseline rather than being penalized.

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 ('Returns saved screenshot layouts') and scopes it to one variant and language, enumerating the payload (phone-format layouts, editor link, editing read receipt). An agent can distinguish it from save_layout/sync_layout/transform_layout by the 'returns' framing, though no sibling is named explicitly.

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?

Usage is only implied: 'Read-only' and the phone-format caveat suggest a retrieval step, but the description never says when to call it versus save_layout, sync_layout, or get_editing_reference, nor that language must be supplied before transform_layout. That key routing information lives only in the schema's language description.

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