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

Annotations are absent, so the description carries full burden. It discloses that it relies on latest CDN platform fee data, which is a useful behavioral trait. However, it does not explain the return format (e.g., a comparison report vs a single number), whether it makes external network calls, or how optional parameters like state and shippingCost affect the calculation.

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 two sentences, front-loads the primary purpose, and includes a relevant detail (CDN fee data) without fluff. It earns its length.

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 output schema and no annotations, the description should clarify what the tool returns and how the comparison is presented. It fails to do so, leaving the agent uncertain about the output structure. It also doesn't mention whether all platforms are always included or if the result is an array.

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 schema provides descriptions for all four parameters (100% coverage), so the description doesn't need to add parameter-level details. It does not provide any additional semantics beyond the schema, which aligns with the baseline 3 for high schema coverage.

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 the verb 'Compare' with a specific resource ('real profit across reselling platforms'), names concrete platforms (eBay, Poshmark, Mercari), and adds 'after fees' to clarify the scope. This distinguishes it from sibling tools like calculate_dropship_profit or calculate_break_even.

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 implies the tool is for comparing reselling platform profits, but it does not explicitly state when to use it over alternatives such as calculate_dropship_profit or calculate_break_even, nor does it provide exclusions or conditions. The mention of 'latest CDN platform fee data' suggests a dependency but not when to prefer this tool.

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