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

Annotations only declare readOnlyHint=true; the description adds real behavioral context beyond that: costs are hourly price estimates (data may be stale), inputs must be bought at or below target float, some results are locked teasers with unlock timing, and the response carries execution_notes about what to verify before buying. It stops short of 5 only because it doesn't characterize the freshness window or any rate limits.

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 tool's purpose and return contents, then the caveats (float requirement, hourly estimates, execution_notes) and the auth boundary. Dense and largely waste-free, though the opening clause strings three deliverables together in one run-on sentence rather than structuring them.

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?

There is no output schema, so the description carries the return-value burden and does so: it names the three payload sections, the caveat field (execution_notes), and the data-quality limitation of hourly estimates. With only one optional enum parameter and a read-only annotation, nothing an agent needs in order to call this 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?

The single 'type' parameter has a full schema description with enum values and a default, so schema coverage is 100%. The description never mentions the feed selector, adding nothing beyond the schema. Per the high-coverage baseline, a 3 is appropriate here.

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 and resource (get the free preview of the SkinGrind Trade Up scanner) and enumerates exactly what the response contains: featured Trade Ups with full recipes, active contract count, and locked teasers. It is immediately distinguishable from siblings like get_case_roi_ranking or browse_bargains, which are ranking/browsing tools rather than a preview feed.

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?

The description clarifies the context of use by contrasting the free preview with the paid path: 'Full recipes for the whole feed need a SkinGrind account and the authenticated server.' That tells the agent when this tool is sufficient and when the user must authenticate, but it never names an alternative tool or states explicit exclusions, so it stops short of a 5.

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