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

With no annotations, the description carries the burden of behavioral disclosure. It signals this is a free, read-only information tool by leading with '[FREE]' and using 'Returns' for the expected outputs. It does not explicitly say 'does not purchase anything,' but the wording strongly implies it only supplies information. It also discloses pricing and network context (x402 on Base), which is useful behavioral context.

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 compact and front-loaded: it opens with the key value proposition, then lists exactly what is returned and the specific pricing tiers. Every sentence adds information, with no filler or repetition.

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 zero-parameter information tool with an output schema present, the description is fully sufficient. It tells the agent what data it will get (current ad, tier prices, purchase flow) and places the tool in its domain (AIARENA ads, x402 payments on Base). Nothing essential is missing for correct selection and invocation.

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?

The tool has zero parameters, so the baseline of 4 applies. There is no parameter semantics burden, and the description correctly focuses on the tool's return contents rather than inputs.

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 uses a specific verb and resource: 'See the current AIARENA blimp ad' and 'buy your own flying ad slot.' It clearly lists the concrete outputs (current ad, tier prices, purchase flow), which makes its purpose obvious and distinguishes it from the sibling submit/purchase tools like aiarena_ads_submit and aiarena_ad_submit.

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 makes the use case clear: retrieve current ad info, pricing, and the purchase flow. There is no explicit 'use this instead of X' statement, but the informational nature and the '[FREE]' marker imply this is the read-only/pre-buy reference tool, while siblings handle the actual submission. A more explicit exclusion of the submit tools would make it a 5.

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