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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety and external-reach behavior are covered. The description adds that results are 'normalized listing cards', a small useful detail, but says nothing about rate limits, ranking, or result caps beyond what the schema documents.

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, purpose lead, usage second — well front-loaded with no filler. The stray 'category' mention is a small inaccuracy rather than bloat.

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 an output schema present and annotations covering safety, the description only needs to convey purpose and when-to-use, which it does. The only gap is the inaccurate 'category' reference and no note on which filter fields exist.

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 coverage is 100%, so baseline is 3. The description references keyword and pagination, which map to real params, but it also mentions an 'optional category' input that does not exist in the schema (the filter param is listing_type), so it adds no accurate meaning beyond the schema.

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 ('Search eBay listings by keyword') and names the downstream sibling action ('opening a specific listing for more detail'), letting an agent distinguish it from ebay_item without opening either schema.

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?

Explicitly frames the tool as a discovery step that precedes opening an individual listing, which is real when-to-use guidance. It stops short of naming ebay_item directly or stating exclusions, so it is not a full 5.

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