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

Annotations are minimal (no readOnlyHint true), and the description adds valuable behavioral context: it records usage/query metadata, anchors windows to the latest sale date, and clarifies that median_usd is a mixed-grade reference. These go beyond the schema and annotations, though it doesn't mention pagination or error behavior.

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?

The description is a compact paragraph that front-loads the core purpose, then adds anchoring details and a usage caveat. It is efficient and well-ordered, though a few clauses could be tightened without loss of meaning.

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?

Given the tool has 4 optional parameters with enums and an output schema, the description covers the main purpose, filters, anchoring, and the median_usd vs card_price distinction. It also notes usage recording and the 50-leader limit. The only minor gap is not elaborating on the definition of 'verified sales count' or the exact sort order, but these are inferable from the title and context.

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 100% with clear per-parameter descriptions, so the baseline is 3. The description repeats some schema info (e.g., window anchoring, PSA10 meaning) and adds context about median_usd vs card_price, but that pertains to response fields, not parameter semantics. It doesn't meaningfully enhance the parameters beyond the schema.

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?

The description clearly states the tool lists most-traded graded Pokémon cards by verified sales count over configurable windows, with filters for language and grading company. This is a specific verb+resource+scope and distinguishes it from siblings like market_movers (price movers) and recent_sales (individual transactions).

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?

It provides an explicit alternative for precise pricing ('use card_price for a precise per-grade quote') and clarifies the window anchoring behavior, which guides when to use this tool. However, it does not explicitly name other siblings like market_movers or state when not to use this tool, leaving some inference to the agent.

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