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

Annotations already declare readOnlyHint=true and openWorldHint=true, covering the safety profile. The description adds nothing beyond that — no note on whether the ID must be a live listing, whether removed/ended listings resolve, or any rate/coverage caveat. It neither contradicts nor enriches the annotations.

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?

Three words with zero waste, but the terseness crosses into under-specification rather than efficiency. It is front-loaded by default but carries almost no informational payload.

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?

An output schema exists so return values needn't be described, the single parameter is fully documented, and annotations carry the safety profile. Given this low complexity, the description is minimally sufficient, though it leaves the agent guessing at what 'details' encompasses.

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%, with item_id fully documented including a concrete example (196435705622). The description adds no further meaning beyond the schema, so the 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?

The description names the resource (an eBay item) and implies a detail-retrieval operation, which distinguishes it loosely from siblings like ebay_search or ebay_seller. However, 'details' is a vague noun with no verb, and it essentially restates the tool name without specifying what kind of detail (price, bids, shipping, seller, condition) is returned.

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 guidance on when to use this tool versus ebay_search, ebay_seller, or the live-stream siblings. An agent must infer that this is the lookup-by-ID tool, and there are no stated prerequisites or exclusions.

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