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

With no annotations, the description carries the full behavioral burden. It does disclose key behavior: equal spacing, a maximum-gap enforcement, and the returned items. However, it does not explain how the tool behaves if equal spacing cannot satisfy the maximum gap, nor what 'positions' means relative to the run, leaving some ambiguity.

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?

The description is a single concise sentence that front-loads the purpose, lists the outputs, and then states the key constraint. Every clause adds meaningful information and there is no redundancy with the schema.

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 three-parameter calculator, the description and schema provide the essential inputs and outputs. However, the output format for positions, handling of edge cases when the max gap cannot be met, and unit assumptions are not fully clarified. These gaps make the description slightly incomplete for fully autonomous invocation without probing.

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?

The schema already describes run_mm and max_gap_mm, and the description reinforces max_gap with the sphere-code example. It also helps contextualize baluster_width_mm as the width of the baluster/spindle, but it does not explain parameter relationships or output representation. With 67% schema coverage, this is adequate but not fully compensating.

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 states the specific operation: equal baluster/spindle spacing for a run, and enumerates the outputs: number of balusters, exact gap, and positions. This is not a tautology and clearly differentiates the tool from sibling calculators like linear_cutting_optimizer or board_feet_calculator.

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 phrase 'for a run' plus the 4-inch/100 mm sphere code rule gives a clear scenario: when an agent needs to lay out balusters or spindles with a maximum gap constraint. There are no explicit exclusions or alternative tool references, so it does not earn a 5, but the usage context is clear.

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