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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds a genuinely useful non-annotation trait — the flat 5-credit cost per successful run — but says nothing about result volume, pagination, or what happens when a seller is not found.

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 very short sentences, with the capability front-loaded and the cost disclosure second. Nothing is padded and both sentences carry information the agent needs.

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 single-parameter, read-only lookup with annotations covering the safety profile and no output schema, the description covers what it returns and what it costs, which is enough to invoke it correctly. It falls short only on sibling disambiguation against run_ebay_seller_feedback and run_ebay_seller_items.

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% and the schema already spells out that the value may be a username or a store URL with an example. The description's "by username" adds only marginal clarity and doesn't expand on accepted formats or URL normalization.

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?

States a specific verb and resource ("Get an eBay seller/store profile by username") and enumerates the returned content (feedback, ratings, store details). It is clear on its own, but it does not distinguish itself from the adjacent siblings run_ebay_seller_feedback and run_ebay_seller_items, and the mention of "feedback" actually blurs the boundary with run_ebay_seller_feedback.

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?

There is no when-to-use or when-not-to-use guidance and no reference to any alternative tool. Given that run_ebay_seller_feedback and run_ebay_seller_items exist as clearly overlapping siblings, the absence of routing guidance is a real gap.

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