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

Annotations already declare read-only and idempotent behavior; the description adds valuable behavioral context by referencing the Cycleshire chart, real UK listing data, and the wheel-diameter sizing for children. It does not describe edge cases or how missing data is handled, but the added context is meaningful.

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 purpose is front-loaded and the example is easy to parse. The chart URL, methodology note about inside-leg-to-seat-tube, and UK data refinement are somewhat extra, but they add context without becoming filler.

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?

Given the two-parameter schema and an existing output schema, the description covers the core input semantics, an example, and the children exception. It does not discuss optional categories or odd inputs, but an agent would still be able to determine how to call the tool.

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 documents heightCm fully and provides category enum values but no description for category, so coverage is partial. The description notes that sizing depends on height and category and that children are sized by wheel diameter, which adds meaning. It still does not elaborate per-category sizing semantics or default behavior when category is absent.

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 immediately identifies a concrete resource: frame-size recommendation based on rider height and bike category. The worked example and the children/wheel-diameter case make it clear and help distinguish it from buy-guide or spec-sheet sibling tools.

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 example gives an explicit trigger for when to use the tool, and the children statement establishes a conditional sizing path. It does not explicitly name sibling alternatives or state when not to use this tool, so exclusions are supplied only indirectly.

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