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

Annotations already carry readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false. The description adds value beyond these by identifying the authoritative data source (FGAA-reviewed Gem Data Tables) and the trade-name resolution behavior. No contradiction with annotations; 'and more' is consistent with openWorldHint=false.

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?

Two tightly-written sentences with zero filler. The property list is front-loaded first, followed by the source authority and trade-name behavior. Every clause earns its place.

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?

A single parameter with 100% schema coverage, rich read-only annotations, and an output schema present. The description fully equips an agent to call it correctly — what to pass in and what properties come back. Nothing an agent needs 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% — the species parameter is fully described with examples in the schema. The description adds genuine extra value by documenting the trade-name resolution behavior (sapphire→corundum, tsavorite→garnet) that isn't in the schema, raising it above the baseline 3.

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 a specific resource (physical properties) and enumerates exactly which properties are returned (Mohs hardness, refractive index, specific gravity, birefringence, crystal system), plus example species. This clearly distinguishes it from siblings like define_gem_term (definitions) and faceup_size_estimate (size).

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 enumerated property list makes the use case clear — this is for physical data, not definitions or care. It explicitly states it accepts trade names and how they resolve ('sapphire' to corundum, 'tsavorite' to garnet). It doesn't name alternative tools or when-not-to-use, but the scope is evident from the properties listed.

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