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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so safety is covered. The description adds genuinely non-structured context: the data is third-party lab output and each report carries a link to verify on the lab's own site, which matters for trust/attribution. It stops short of describing behavior on no-match or multiple matches, keeping it at 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?

Three tight sentences: capability first, payload second, routing third. No filler, and the most decision-relevant constraint (the sibling handoff) lands last where it is easy to act on.

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's field enumeration (lab, lot, test date, identity, purity, potency, report link, verification link) is necessary and present. For a one-parameter read tool, 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 coverage is 100% and the 'query' parameter already documents lot-number-from-vial-label vs product name/slug. The description's 'by lot number or product' restates that rather than adding format or matching semantics, so 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?

The description opens with a specific verb and resource ('Read third-party lab reports (COAs)') and states the two lookup keys (lot number or product). It also enumerates what a report contains, so an agent can distinguish it from get_product and search_products without opening a 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?

It states the use case explicitly ('questions about testing, purity or a lot number') and names the alternative with its own scope ('Use get_product for prices and stock'). This is a clean when-to-use / when-not-to-use routing rule.

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