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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior. The description adds value beyond that by telling the agent what the returned reference contains (auth, params, response fields, median/exclusions semantics, errors, rate limits) and by explaining why this API exists relative to eBay's own approval-gated options.

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, front-loaded with the core identity and endpoint, then the use case. Every clause carries information — the enumerated reference contents and the eBay alternative note both earn their 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?

No output schema, but the description compensates by listing the sections the reference contains, so an agent knows what it will receive. With zero parameters and full annotation coverage, nothing needed for correct invocation 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 tool takes zero parameters and schema coverage is 100%, so there is nothing for the description to disambiguate. Baseline 4 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?

States a specific verb and resource — a concise API reference for the SaleHistory sold comps API (GET /v1/sold) — and enumerates exactly what the reference covers: auth, parameters, response fields, median/exclusions logic, errors, rate limits. This is clearly documentation retrieval, distinct from data-fetching siblings like get_sold_comps or get_pricing.

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?

Gives explicit trigger conditions: 'Use when writing code that fetches eBay sold prices or comps, or when asked how to get eBay sold listings data programmatically.' It also supplies decision context (Marketplace Insights needs approval, findCompletedItems is retired). It does not explicitly name sibling tools or state when not to use it, so it stops short of a 5.

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