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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety and open-world reach are covered. The description adds which data categories (policies, shop reputation) are present, but says nothing about auth requirements, rate limits, or error behavior for invalid ids. With annotations carrying the safety profile, this is adequate but not rich.

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 sentences, zero waste: the return payload leads, the differentiation from reverb_search follows, and the id provenance is last. 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 single-item detail fetch with a full output schema, the description need not explain return values, yet it helpfully previews them. The id provenance closes the loop for sourcing the required parameter. Only minor behavioral/gap context is absent.

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% and the parameter is fully documented, so the schema does the heavy lifting. The description's restatement of the id ('listing's numeric id, from a search result's own listings[].id field') largely repeats the schema description, adding only marginal emphasis on the numeric type and source field. Baseline 3 is correct.

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+resource ('Full normalized listing-detail data for one Reverb listing') and enumerates concrete returned fields (description, photos, policies, shop reputation). It explicitly contrasts itself with the sibling reverb_search, so an agent can tell the detail-fetch from the search 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?

It establishes the selecting condition by positioning itself as 'richer than the flattened summary reverb_search returns per listing,' which implies fetch detail when search's summary is insufficient. It also tells the agent where to source the id. It stops short of an explicit when-not or mandatory prerequisite, so it is clear context without full routing rules.

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