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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the description needn't restate safety. However, it claims 'Batch lookup of multiple creative IDs' and 'Returns None for failed lookups while continuing others,' which directly contradicts the schema that accepts only a single integer creative_id. This misrepresents the tool's actual behavior and could mislead the agent. The description adds no other behavioral detail beyond what annotations cover, and the batch claim is a significant negative.

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 well-structured with clear sections (WHEN TO USE, RETURNED INFORMATION, FEATURES) and front-loads the core purpose. It is longer than necessary, with some redundancy (e.g., 'by their IDs' and 'Looks up each creative ID individually'), but remains readable and organized. The batch claim adds noise but doesn't harm overall structure.

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?

For a simple one-parameter read tool, the description provides extensive information about returned fields and features. However, it overpromises batch capability and doesn't clarify that only one ID can be queried at a time. Since there is no output schema, the description's list of returned information is useful, but the misleading batch feature and missing clarification about the single-ID constraint leave gaps that could cause incorrect usage.

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% with a single parameter creative_id described as 'creative id to be query.' The description adds minimal parameter insight beyond repeating that lookups are by ID. It doesn't clarify the integer format or that only one ID can be provided per call. Baseline 3 is appropriate since the schema carries the load, but the description misses the chance to correct the singular/plural confusion.

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 clearly states the tool's purpose: 'Get detailed information for specific creative assets by their IDs.' It uses a specific verb and resource, and distinguishes from siblings like search_library_creatives_by_name by focusing on ID-based lookup. However, the plural 'IDs' contradicts the singular integer parameter, causing slight ambiguity.

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 'WHEN TO USE' section lists concrete scenarios: getting metadata, verifying properties, auditing, and validating IDs. This provides clear context for when to invoke the tool. It does not explicitly state when not to use it or mention alternatives, but the use cases are specific and helpful.

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