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

Annotations already cover readOnly/openWorld/idempotent, but the description adds real operational context beyond them: 15-minute caching, a cost model (1 request per completed search, cache hits billed, failures free), and a docs link. It stops short of auth or rate-limit details, so not a 5.

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?

Front-loaded with the core action, then terse cost/cache facts and a docs pointer in one dense sentence. Every clause carries information, though the semicolon-chained cost sentence is slightly packed.

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 usefully characterizes the return payload and adds caching/cost behavior, and annotations carry the safety profile. Pagination behavior is left to the schema, but nothing an agent needs to call 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 description coverage is 100%, so the schema already documents all five parameters including the q format, pagination, count cap, and product_line naming. The description only alludes to 'by keyword' and adds no syntax or format beyond the schema, so the baseline 3 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+resource ('Search TCGplayer products by keyword') and enumerates what comes back (catalog identity, market-price estimate, active seller asks), which implicitly separates it from the sold-comps sibling tcgplayer_sales. An agent can identify the tool's job without opening the schema.

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?

Usage is implied by 'search products by keyword' and the return contents (current asks vs sold data) hints at when it beats tcgplayer_sales, but the description never names an alternative or an explicit when-not condition. Adequate but leaves routing to inference.

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