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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower. The description still adds value by disclosing the return semantics (m³ to remove and an 8m³-truck count), which tells the agent the output shape and the truck-capacity assumption used.

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 front-loaded sentences that state purpose, usage, inputs/outputs, and a cross-reference. Mostly earns its place, though 'Use for construction' is slightly redundant filler next to the more specific use cases.

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 annotations covering safety and an output schema present, the description is complete enough: it names inputs, output values, and a related-bundle pointer. Minor gap is that it doesn't explain how soil_type/swell affects the result, though the schema largely covers that.

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 all four parameters including the soil_type enum and its swell values, giving a baseline of 3. The description adds units and the term 'bulking factor', but that term only loosely maps to the schema's soil_type parameter, adding little beyond the schema.

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 (compute) and resource (excavation volume in m³ and truck loads), with concrete use cases (foundation, pool, trench). This clearly distinguishes it from adjacent siblings like calculate_volume, calculate_garden_soil, or calculate_gravel_quantity.

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?

Gives clear usage context ('Use for construction', foundation/pool/trench) and points to list_bundles for related 'construction' calculators. However, it does not explicitly name which sibling to use instead or state when NOT to use it (e.g., vs a plain volume calculator).

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