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

Description discloses error behavior for free accounts and prerequisites (paid membership). No annotations are provided, so the description carries the full burden; it covers key behavioral aspects but could mention additional side effects or return details.

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?

Description is relatively concise but includes redundant details (supported sizes also in schema). However, the additional context about membership and detection adds value, so the verbosity is justified.

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?

Given the schema fully covers parameters and no output schema exists, the description provides sufficient context for usage. It could mention what returns or side effects occur on success, but the core usage is complete.

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 descriptions cover all parameters 100%, including URL requirements and supported sizes. The description adds context about membership and errors, though the parameter meanings are already well-defined in the schema.

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?

Clearly states the action ('Creates a new banner ad'), specifies the resource (banner ad), and distinguishes from sibling tools by mentioning automatic location detection from image size, which is unique to this tool.

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?

Provides explicit conditions: HTTPS requirement, supported dimensions, membership levels, and error conditions for free accounts. This gives clear guidance on when this tool should be used versus alternatives.

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