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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety behavior is covered. The description adds only "Returns converted size" (already implied by the output schema) and no precision/rounding or edge-case behavior. No contradiction with annotations, but little value beyond them.

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 core purpose, so it is not bloated. However, the input list is wrong and the trailing list_bundles pointer is off-target, so parts of the brevity come at the cost of accuracy.

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?

The output schema covers the return value, so that need not be explained. Still missing: how gender should be expressed (it is only implicit in the us_m/us_w enum), whether conversions round, and any routing between this and calculate_shoe_size_convert. The phantom "gender" input leaves a real gap.

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%, so the baseline would be 3, but the description actively misinforms: it lists inputs as "size, from, to, gender" while the schema defines "value" (not "size") and has no "gender" parameter at all — gender is encoded in the us_m/us_w enum values. This sends an agent looking for a parameter that does not exist.

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 (Convert) and resource (shoe sizes) and enumerates the supported systems (EU, US men/women, UK), which is enough to understand the operation at a glance. It does not distinguish itself from the near-identical siblings calculate_shoe_size_convert and calculate_shoe_size, so it falls 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?

"Use for online shopping" is a vague, non-actionable context with no when-not guidance. It points the agent to list_bundles for "related conversions calculators" rather than to the obvious sibling calculate_shoe_size_convert, which is the alternative an agent actually needs to disambiguate.

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