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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world, so the safety profile is covered. The phrase 'No new search or analysis' adds a genuine behavioral guarantee: calling this triggers no computation, scan, or cost, which distinguishes it from adjacent tools that initiate work.

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?

Two sentences, zero filler, and the affirmative scope statement is front-loaded ahead of the exclusion. Every clause earns its place.

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 return values need no explanation; the input surface is a single ID. Given the annotations and output schema, the description supplies everything an agent needs to select and 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 description coverage is 0%, so the description must carry the meaning of brandId. 'This brand's' implies the ID scopes results to one brand, but format, source, or lookup guidance is absent. With a single obvious parameter, this is minimally adequate rather than compensating for the coverage gap.

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 gives a specific verb ('Read') and resource ('this brand's saved public ads and research notes'), which is enough to separate it from search_library_ads or analyze_library_ad. It does not explicitly name the siblings it contrasts with, but the 'saved' framing is a meaningful scope qualifier.

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?

'No new search or analysis' establishes a boundary condition, implying this is for retrieval of previously saved items rather than discovery. However, it never names the alternative tool (e.g., search_library_ads) or states prerequisites, leaving the agent to infer routing.

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