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

Annotations already declare non-read-only, non-destructive, open-world behavior, so the description adds genuine context: it discloses the return shape (result plus identifier) and that validation/platform errors can come back, and it clarifies the operation's scope ends at library creation. It omits account/permission requirements and what happens on duplicate logo creation.

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 action, with the returning-behavior and scope-boundary statements each earning their place. 'Using the supplied fields' is the one filler phrase that adds nothing.

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 correctly compensates by describing the return value and error outcome. However, for a mutation tool with three fully undocumented parameters and no annotation coverage of auth/rate limits, an agent still lacks enough to build a correct call.

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 parameter meaning, yet it only says 'using the supplied fields.' Nothing explains what image_library_id (the sole required param) refers to, nor how domain_name and business_name (maxLength 50/25) relate to the logo or whether they are optional.

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 (Create) plus a specific resource (business logo extension) and its location (the account's Google Ads asset library). It is clearly distinguishable from the many create_google_*_extension siblings and from create_microsoft_business_logo_extension via the platform and asset type named.

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?

The final sentence explicitly carves out the boundary: creating in the asset library is separate from attaching to a campaign, which routes the agent away from add_extensions_to_native_campaign. It does not name that sibling or state prerequisites/plan requirements, so it falls short of explicit when/when-not guidance.

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