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

Annotations already establish readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful context beyond that: this is a fixed, closed set of exactly seven gemstones with a defined attribute list, which tells the agent to expect a small static reference table rather than a searchable or paginated collection.

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?

A single sentence that front-loads the cardinality and subject ('the seven gemstones every cut is measured in') then lists the returned fields. No filler, no redundancy.

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?

With no output schema and no parameters, the description carries the burden of describing return content, and it does so by naming every field plus the nested 'three best cuts'. It could be marginally more complete by stating the container shape (a list of seven gemstone objects), but 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?

The tool takes zero parameters and the schema is an empty object with additionalProperties=false, so there is nothing for the description to disambiguate. Baseline 4 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 names the exact resource (the seven gemstones that cuts are measured in) and enumerates the attributes returned (refractive index, critical angle, dispersion, hardness, specific gravity, plus three best cuts per gemstone). That is far more specific than a restatement of the name. It stops short of distinguishing itself explicitly from siblings like best_cuts_for_gemstone or get_cut_scores, which it partially overlaps with on the 'three best cuts' content.

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?

Usage is only implied: an agent can infer this is the reference lookup for gemstone properties, but the description never says when to call it versus best_cuts_for_gemstone (which also returns best cuts) or cut_in_gemstone. No exclusions or prerequisites are stated.

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