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

With no annotations, the description carries the full burden, and it does disclose the safety profile ("Read-only") plus the item-count bounds (2-6). It also tells the agent what dimensions are compared, which is effectively output content. It doesn't cover failure modes or what happens with fewer than 2 items, so it isn't exhaustive.

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?

Three short sentences, front-loaded with the core purpose, no filler. The parenthetical list of comparison dimensions is dense but each item earns its place by telling the agent what the matrix contains.

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?

No output schema and no annotations, so the description must carry everything — and it covers purpose, sequence, item bounds, and compared fields. Remaining minor gap is what the response structure looks like (matrix layout/columns), but nothing critical to correct invocation 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 100% and the schema documents the accepted formats ("tbk:ID,pdd:ID" or JSON array). The description adds the meaningful constraint that 2-6 items are expected, which is not encoded in the schema — genuine added semantics beyond the structured field.

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 (side-by-side comparison), resource (shelf items), and scope (2-6 items), plus enumerates the comparison dimensions. This clearly distinguishes it from generic search/detail siblings like cps_item_info or search_goods, which return single items rather than a comparison matrix.

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?

"Use after cps_smart_search to justify a recommendation" gives an explicit workflow position and names the preceding sibling, which is strong guidance. It stops short of stating when NOT to use it (e.g., single-item checks should use cps_item_info).

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