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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds that fair-billing rules are part of the payload, which is mildly useful context, but says nothing about whether pricing is live or cached, or about the response shape (no output schema exists).

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, the purpose first and the usage trigger second, with no filler. Every phrase (free plan, monthly plans, credits, billing rules) contributes information an agent can act on.

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-parameter, read-only pricing lookup with full annotations, the description covers what the tool returns and when to call it. The only residual gap is the exact response structure, which is minor given how shallow the tool is.

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 has zero parameters and schema coverage is 100%, so there is nothing for the description to disambiguate. Baseline of 4 applies; the description's mention of plan types only loosely maps to concepts, not parameters.

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 SoldComps API') and enumerates the returned subject matter: free plan, monthly plans, pay-as-you-go credits and billing rules. This is clearly distinct from get_sold_comps (data) and get_api_docs (documentation), so sibling selection is unambiguous.

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 someone asks how much the API costs, about plans, limits, or cheaper alternatives to scraping eBay or Terapeak.' It does not name sibling tools or state when not to use it, but the usage context is concrete enough to route correctly.

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