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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds substantial context beyond them: billing semantics, the uncharged-no-range rule, partial-allowance truncation with `batch.truncated` naming the remainder, plan-based caps, and auth requirements. This is exactly the extra behavioral detail annotations cannot convey.

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?

Four dense sentences, front-loaded with purpose before cost, truncation, caps, and auth. Every sentence carries a distinct operational fact with no filler.

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?

With no output schema, the description still discloses the key return behavior (partial results plus `batch.truncated`), plus cost, caps, and auth. Nothing an agent needs to invoke it correctly 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?

Schema coverage is 67%, so the schema documents most fields; the description still clarifies the string-vs-object duality of each query and that objects carry their own q/category/country/state, implying per-item override of the top-level defaults. It adds real meaning over the raw oneOf structure, though it doesn't spell out default inheritance explicitly.

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?

Opens with a specific verb+resource scoped to a batch ('get_sold_comps for a list of items in one call'), which immediately distinguishes it from the singular get_sold_comps sibling. An agent knows exactly what it does and how it differs from the single-item tool.

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 strong operational context: per-item cost equals a standalone lookup, uncharged items without a range, plan-based batch caps (10 free), and sign-in/API-key requirement. It doesn't explicitly say 'use get_sold_comps instead when you have one item,' but the batch framing makes the alternative obvious.

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