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

The annotations already declare the operation read-only, idempotent, and non-destructive. The description adds useful behavioral context beyond those annotations by noting that an Etsy API key is required and by identifying the API version/endpoint (Etsy Open API v3, getListing). It does not contradict any annotation.

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 is two sentences with no wasted words. It front-loads the core action and identifier requirement, then adds the necessary auth and API version context. Every sentence earns its place.

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 simple one-parameter read-only getter, the description is complete enough: it identifies the resource, the lookup key, the API version, and the auth requirement. The annotations already cover safety and idempotency, and no output schema is needed to understand what a single-listing getter returns.

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?

The schema already fully documents the only formal parameter, listing_id, as a numeric Etsy listing ID. The description mostly restates this requirement and adds the API-key requirement, which is authentication context rather than deeper parameter semantics. With 100% schema coverage, the baseline of 3 is appropriate.

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 states a specific verb ('Get'), a specific resource ('one Etsy listing'), and the key selection criterion ('by its numeric listing ID'). This clearly distinguishes it from the sibling search tools, which retrieve listings by query or shop rather than by a single known ID.

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 clearly implies the correct use case: call this tool when you already have a numeric Etsy listing ID and need that single listing. It does not explicitly name etsy_search_listings or etsy_search_shop_listings as alternatives, so it stops short of giving when-not-to-use guidance.

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