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

Annotations already establish this as read-only, idempotent, and non-destructive. The description adds useful behavioral context: the data comes from a published source, is banded by origin/size, includes stone counts and a computation date, and is a house guide rather than a market index. No contradiction with annotations.

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 dense sentences, front-loaded with the core subject—what costs per carat in AUD—followed by provenance and a concrete usage example. Every sentence contributes.

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 simple two-optional-parameter lookup with an output schema and complete annotations, the description is complete: it names the source, the banding dimensions, the computed date, the stone-count context, and the caveat that this is a house guide. Nothing needed to invoke 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%, so the schema already documents carat and origin. The description reinforces that carat selects a size band and origin is Australian or Ceylon, but does not add meaning beyond the schema; baseline 3 is appropriate.

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 clearly identifies the resource—natural sapphire price per carat in AUD from Ministry of Gems' price guide—and the main question it answers. It does not use a strong imperative verb and does not explicitly distinguish itself from sibling knowledge/property tools, so it falls just short of a 5.

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 gives a concrete use case ('Answers how much is a 2 carat sapphire') and frames the result as a house guide rather than a market index, which tells an agent how to interpret it. It does not explicitly list when not to use the tool or name alternatives.

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