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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, so basic safety is covered. The description adds useful behavioral context beyond annotations: it only returns active listings, states the output fields, and discloses cost as '1 point per returned record'. It stops short of explaining pagination or rate-limit behavior, so a 4 rather than a 5.

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 short sentences with zero waste. The purpose and returned fields are front-loaded, and the cost detail is given immediately after. Every sentence earns its place.

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 simple read-only listing tool with 100% schema coverage and no output schema, the description covers purpose, return fields, and cost. It does not explain pagination behavior or how max_items interacts with point cost, which would help an agent avoid surprises. The definition is largely complete but has a small contextual gap.

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 description coverage is 100%, so seller, max_items, and start_page are fully documented in the input schema. The description adds no parameter-level meaning such as seller format examples, max_items default behavior, or pagination semantics. With the schema doing all parameter work, the baseline 3 is correct.

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 verb and resource: 'List active eBay listings for a seller', and names the fields returned (title, price, condition, image). This clearly separates it from sibling tools like run_ebay_seller or run_ebay_seller_feedback, but it does not explicitly name alternative tools or draw the comparison in the text. A 4 is appropriate: clear purpose, no explicit sibling differentiation.

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 explains what the tool does but gives no when-to-use context, prerequisites, or alternatives. It does not say when a caller should use run_ebay_seller_items instead of run_ebay_item_search or run_ebay_seller. This matches the calibration for a tool with no usage guidance.

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