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

Annotations already establish readOnly, idempotent, closed-world behavior, so safety disclosure is covered. The description adds useful context by showing the output magnitude (0.93 cubic yards / 1.31 tons) and the output unit options (yards, m³, tons, bags), but does not describe return structure or how pricing/currency feeds the result.

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?

Very compact: a concrete worked example first, then a one-line scope statement, then a link. Front-loaded and waste-free, though the URL adds little for an agent.

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 10-param, zero-required calculator with no output schema, the worked example substitutes reasonably for describing output. It omits that the tool also performs cost estimation via price/priceUnit/currency and says nothing about shape handling, but the schema covers those gaps.

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% with enums and defaults documented per parameter, so the schema carries the load. The description's material list and unit mentions (yards, m³, tons, bags) loosely mirror the material and priceUnit enums without adding new 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?

States a specific verb and resource ('Size gravel, stone, sand, topsoil or mulch orders in yards, m³, tons or bags'), making clear it computes material quantities. It does not explicitly name a sibling like concrete_calculator or volume_calculator to route between them, so it stops 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?

Usage is implied by the worked example (a 10x10 ft bed 3 in deep) rather than stated: it never says when to pick it over concrete_calculator or square_footage_calculator, and gives no prerequisites or exclusions.

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