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

Annotations already declare read-only and idempotent behavior. The description adds valuable context beyond annotations: it mentions the credential error behavior and the official API backend. No contradiction with annotations exists.

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 consists of three concise sentences: purpose and scope, output fields, and error behavior. Every sentence earns its place with no waste or redundancy.

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?

The description lists output fields, covers site scope, and discloses the credential error. Since there is no output schema, listing the returned fields is valuable. It does not explicitly state that q or category is required, but the schema covers that. Overall, it is fairly complete for a 12-parameter search tool.

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 75%, so baseline is 3. The description adds only a high-level mention of keyword/category and the 8 sites, without diving into individual parameter meanings. It does not significantly improve parameter understanding over 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?

The description clearly states it searches live eBay listings by keyword and/or category across 8 sites, built on eBay's official Browse API. It also lists the specific fields returned (id, title, price, condition, etc.), which differentiates it from sibling tools like search_ebay_sold and get_ebay_item by scope and output detail.

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 provides clear context (live listings, 8 sites, Browse API) but does not explicitly state when to use this tool versus alternatives like search_ebay_sold. No exclusions or comparisons are given, leaving the usage guidance implied but not explicit.

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