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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely new behavioral context not present in structured fields: the flat 5-point cost per successful run, which lets an agent budget calls. It does not cover error behavior for an invalid ePID, so it stops short of 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?

Two short sentences with zero filler: the resource and returned fields are front-loaded, and the cost caveat follows. Nothing repeats the title or wastes tokens.

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, the description correctly compensates by listing what is returned. Combined with the annotations, an agent has enough to invoke it. The one gap is that the route to acquiring an ePID is not stated, which matters given the dense eBay sibling set.

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 single parameter already documents 'ePID or URL. e.g. 1234567890'. The description's 'by ePID' only partially matches that (it omits that a URL is also accepted), so it adds essentially nothing beyond the schema. Baseline 3 applies.

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 eBay catalog product details by ePID') and enumerates the returned fields (brand, model, rating, price range, specs). It does not distinguish itself from the closely related run_ebay_item or run_ebay_item_search siblings, so an agent must infer that this is the catalog-level product, not a live listing.

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?

No when-to-use guidance, no prerequisites, and no mention of alternatives. It never tells the agent how to obtain an ePID (presumably via run_ebay_item_search) or when to prefer run_ebay_item instead. Usage is only implied by the mention of ePID.

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