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

Annotations already declare readOnly/idempotent/openWorld/non-destructive, so the safety profile is covered. The description adds real behavioral context beyond that: it never starts monitoring, it separates exact matches from merely similar items, and it discloses that the second_hand_gate governs whether size was actually applied. It stops short of latency/cost or region-default behavior, so a 4.

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 primary trigger, then routing alternative, then the fallback rule, then exclusions. Dense and mostly every sentence earns its place, though the routing guidance is slightly more verbose than strictly necessary.

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?

An output schema exists so return values need not be explained. Combined with the strong usage routing, size caveat, and stated exclusions, an agent has everything needed to select and invoke this tool correctly.

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 75% and the schema already documents size, region, and product_url well (including the size gating caveat). The description only adds the timing rule for passing size ('when they state one'); max_results remains undocumented. Baseline 3 fits since the schema carries most of the load.

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 action (compare a fashion product URL) with concrete scope: exact-product comparison with similar alternatives labeled separately. It explicitly distinguishes itself from the sibling watch_item, so an agent can route without opening schemas.

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?

Explicit when-to-use (one URL, wants availability/cheaper/second-hand/other retailer, results now), explicit when-not (photo without URL, generic discovery, styling, non-fashion), and names the alternative watch_item with the trigger phrases that select it. Even handles the ambiguous case by prescribing a fallback.

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