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

Annotations already declare readOnly/idempotent/closed-world, so the description's job is to add scope and result shape; it does both by enumerating the returned layout fields (label size, columns/rows, margins, pitch, equivalent products) and the US-Letter-only universe. The only missing element is guidance on behavior when multiple filters conflict or return nothing.

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 use case, then scope exclusions and the sibling reference — no filler sentences. The long run of quoted example queries is useful for matching but is the one portion that could be trimmed.

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?

For a read-only, all-optional-parameter lookup with a full output schema, the description covers trigger, scope boundaries, sibling handoff, and result contents. 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% and each of the three params is already documented with examples, so the baseline is 3. The description's example queries hint that free-text phrasing is acceptable, but it adds little about how kind/query/per_sheet combine or which takes precedence.

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 ('Searches the supported US Letter label sheets by product number, label size, labels per sheet or use') plus exactly what it returns. It also explicitly separates itself from generate_label_sheet, so an agent can route without opening either 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?

Gives the triggering user phrasings ('avery 5160 size', 'which labels for return address'), names the alternative tool for the printing case, and states two negative scopes (no A4 sheets, no label-maker tape). When-to-use, when-not, and the alternative are all explicit.

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