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

Annotations already declare readOnly/openWorld/idempotent/non-destructive. The description adds useful interpretive context by clarifying that the returned price is the seller's asking price on a live listing and by enumerating the current state fields (offer/inventory state, condition, shipping rates). This goes beyond the annotations without contradicting them.

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 a single compact sentence that front-loads the purpose and then lists the returned data fields without elaboration. Every clause contributes either to scope, parameter semantics, or result interpretation; there is no filler.

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 tool, the description covers what it returns (title, make, model, year, finish, condition, seller description, prices, state, categories, photos, shipping rates), how the ID is obtained via reverb_search, and how to interpret the price field. The annotations cover safety/idempotency, so nothing needed to call it correctly is missing.

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 input schema already provides 100% coverage for the single listing_id parameter, and the schema description gives an example and explicitly ties the value to reverb_search's id. The tool description only restates 'by listing ID' and does not add new parameter detail, so the baseline score 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 opens with 'One Reverb.com listing in full, by listing ID,' which names a specific verb (retrieve/get), a concrete resource (a single Reverb listing), and the lookup key. Listing the full set of returned fields and mentioning that the price is the seller's asking price distinguishes this from reverb_search, reverb_categories, and reverb_shop.

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?

It is clear from 'by listing ID' that this tool is for fetching a specific listing rather than searching or browsing; the schema's note that the ID comes from reverb_search reinforces when the agent should have a suitable ID. There is no explicit 'when-not-to-use' or alternative routing, but the intended context is reasonably clear.

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