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

Annotations already declare readOnlyHint=true and destructiveHint=false, covering the safety profile. The description adds behavioral details beyond that: the default scope (whole library), pagination requirement (follow next_cursor), and limit constraint (<=50). It also mentions 'trust scope' which indicates the scope parameter controls filtering. These are not in the annotations, so the description adds meaningful behavioral context. It does not contradict annotations.

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?

The description is front-loaded with the core purpose, which is good. However, it includes a lengthy tangent about upload instructions and a URL that is unrelated to the tool's primary function. While this serves as a when-not-to-use note, it could be more concise. The latter part is terse but dense. Overall, it has some bloat but is not overly long, earning a middle score.

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?

The tool has 8 optional parameters with no schema descriptions, and the description only explains a few (scope, limit, cursor). It omits guidance on q, sort, created_from/to, folder_name, leaving agents to guess their purpose. The output schema exists, which may cover return values, but parameter semantics are significantly incomplete. For a listing tool with many filters, this is a notable 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 description coverage is 0%, so the description must compensate for the 8 parameters. It only partially addresses a few: 'scope' (via 'trust scope' and default), 'limit' (via 'use limit<=50'), and 'cursor' (via 'follow next_cursor'). Parameters like q, sort, created_from/to, folder_name are not explained at all. The description adds minimal value for most parameters and fails to guide the agent on how to use the filtering options.

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 states a specific verb and resource: 'List owned creatives; default is the whole library.' It clearly identifies the tool's function (listing creatives) and distinguishes its scope from other creatives tools like creatives_get (single item) and creatives_list_folders (folders only). The phrase 'default is the whole library' adds important context about the default behavior, making the purpose unambiguous.

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 description provides explicit when-to-use guidance by stating 'List owned creatives' and also when-not-to-use: 'For upload/how-to help, give [Creative library]... No list call is needed just for instructions.' It also gives operational constraints: 'trust scope, use limit<=50 and follow next_cursor with unchanged filters.' This clearly tells the agent when to invoke this tool and how to handle pagination and limits, with no ambiguity.

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