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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds useful scope beyond that by naming exactly what data comes back (plan tiers, credit model, fair-billing rules), which tells the agent this is a static informational lookup rather than a live query. No auth or rate-limit details, but none are needed for a zero-param pricing read.

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 resource and its contents come first, followed by the usage trigger, so the essential information is 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?

For a zero-param, read-only info tool with no output schema, the description adequately conveys what will be returned by listing the pricing components. Minor gap: it does not hint at the response shape or whether pricing is versioned/dated, but that is not essential to invoke it correctly.

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, so the baseline is 4. There is nothing to disambiguate and the description correctly does not invent parameter discussion.

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: 'Get current pricing for the SaleHistory sold comps API', and enumerates the pricing content (free plan, monthly plans, pay-as-you-go credits, fair-billing rules). It does not explicitly name sibling tools like get_api_docs or search_guides, but the pricing-vs-documentation split is clear enough to separate it.

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 explicit triggers: 'Use when someone asks how much the API costs, about plans, limits, or cheaper alternatives to scraping eBay or Terapeak.' It gives clear positive conditions but no when-not guidance or explicit routing to a sibling tool.

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