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

Annotations only declare readOnlyHint=false, destructiveHint=false and openWorldHint=false; the description adds the meaningful context that the plan is immutable, is separately confirmable, and does not mutate advertising entities. It stops short of disclosing plan lifetime/expiry or what happens to a plan that is never confirmed.

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 short sentences, front-loaded with the plan concept and the non-mutation guarantee. No restatement of the tool name or filler.

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?

With an output schema, full annotation coverage and a richly described nested input schema, the description carries enough for correct invocation. The remaining gap is workflow-level: it never names the confirm/cancel tools or states that the plan must be confirmed before any ad state actually changes.

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% and the nested schema already explains storeId format, selector fields, the SET_STATE/SET_NAME action shape, and the 1-20 operation limit. The description only echoes the change types, adding little beyond the schema (it does not, for example, clarify how selector combinations are scoped), 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?

The description names a specific verb (prepares) and a precise resource (an immutable, separately confirmable Amazon Ads plan for product ads), and states exactly what the plan covers: ad state changes and supported Sponsored Brands ad names. The phrase 'persists an internal plan without changing advertising entities' cleanly separates it from the apply_* siblings.

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 makes clear this is the staging step (prepare then separately confirm) and that nothing is applied yet, which is the key usage decision against apply_product_ad_changes. It does not explicitly name confirm_workflow_plan/apply_product_ad_changes as the next step, nor does it state exclusions such as when a direct apply is preferable.

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