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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so safety is covered. The description adds real value beyond them by disclosing the implicit filter (only retailers with active listings) and the returned aggregates, including out-of-stock counts and observation recency, which an agent needs to judge data freshness.

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 with no filler: the first defines the resource and its returned fields, the second explains the downstream contract. Scope and the key output are front-loaded.

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?

There is no output schema, and the description compensates well by naming the returned fields and the retailerId contract. Minor gaps remain, such as result ordering or whether the list is paginated, but for a zero-parameter, closed-world listing tool this is nearly complete.

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 tool takes no parameters, so there is no parameter semantics to explain and the baseline of a 4 applies. The description sensibly uses its space on scope and outputs rather than on inputs.

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 (list retailers) plus the exact scope: only retailers where the organization has active listings. It also enumerates the returned metrics (listing count, out-of-stock count, last observation time), which distinguishes it clearly from siblings like radar_list_brands or radar_search_listings.

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?

Provides a strong routing signal by naming the two sibling tools (radar_search_listings, radar_check_stock_outages) that consume the retailerId this tool returns, implying it is the prerequisite step before those calls. It does not give explicit when-not-to-use conditions, but the scoping to 'active listings only' implicitly excludes retailers with no activity.

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