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

Annotations already establish readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds useful non-schema context: it is free of fees and requires no authentication, which helps an agent understand side effects and prerequisites beyond what annotations alone convey.

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 appropriately short and front-loaded, with the core purpose stated first and a direct usage instruction second. There is minor redundancy between 'Free' and 'no fees', but overall it is tight and well structured.

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 read-only validation tool, the description covers what it validates, against what, the lack of auth/fees, and when to use it. The extensive input schema and presence of an output schema mean the agent has everything needed to invoke it correctly without further elaboration.

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?

Input schema description coverage is 100%, so the schema already documents all parameters richly, including the kind enum and the full listing/proposal object shapes. The description adds no additional parameter-level detail, but none is needed given the schema's completeness.

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 action, 'pre-flight validation', with a clear resource ('a listing or proposal') and target ('against the platform schemas'). It also differentiates itself from the concrete sibling tools it precedes, market_post_listing and market_propose.

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?

'Always validate before market_post_listing or market_propose' is explicit when-to-use guidance naming the exact counterpart tools. This leaves no ambiguity about when the agent should call this tool rather than directly posting or proposing.

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