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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint. Description adds behavioral detail about sanitized output (provider/cost details hidden), which goes beyond annotations. No contradiction. Could provide more about pagination or rate limits, but for a simple list tool, it is adequate.

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 concise sentences with clear verb-first structure, parenthetical clarification of sanitized output, and actionable usage tip. No filler.

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?

With no parameters, read-only annotations, and an output schema present, the description fully covers purpose, usage, and sanitization behavior. No additional details required for a list tool.

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?

Tool has 0 parameters, so baseline is 4. Description adds no parameter-specific details needed; it references modelCode for another tool, which is not a parameter here. Schema covers all (empty) properties.

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?

Description uses specific verb 'List' and identifies exact resource 'AI image-generation models' with scope 'exposed to merchants'. It also references usage for picking a modelCode for generate_post_cover, distinguishing it from sibling tools like generate_image and generate_post_cover.

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?

States explicit usage context: 'Use to pick a modelCode for generate_post_cover.' Clear when to use, but does not explicitly mention alternatives or exclusions. Provides sufficient guidance for model selection.

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