geometry.volume_sphere

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

Beyond the readOnly/idempotent/openWorld annotations, the description discloses numeric behavior that matters: π is computed with mpmath at 50 digits and the result is returned as a 30-significant-digit string, and the output unit is the cube of the input length unit. It does not describe error handling for negative or non-numeric input, which keeps it just short of full coverage.

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?

Four short sentences, front-loaded with the formula, then unit semantics, then precision policy, then the radius-vs-diameter warning. No filler and no repetition of structured fields.

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 one required parameter, annotations covering safety, and an output schema handling return structure, the description supplies everything else an agent needs — input type and constraint, unit semantics, and precision policy.

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 0%, so the description carries the entire burden and does: it specifies the parameter is a Decimal-format string, must be at least 0, and is a radius rather than a diameter. This adds real meaning the bare schema property 'radius: string' does not provide.

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 opens with a specific verb and resource plus the exact formula, '(4/3) * π * r³', so the operation is unambiguous. It also distinguishes itself from a diameter-based alternative by stating the radius must be supplied, not the diameter.

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?

It gives a clear constraint for correct invocation (radius, not diameter; radius must be ≥ 0; Decimal string) which is exactly the failure mode for this kind of tool. It does not reference sibling volume tools, but no ambiguity is likely given the explicit formula and input constraint.

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