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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds useful scope context (clearances and connections are considered, not just raw dimensions), but says nothing about how authoritative the clearance figures are, what happens on 'missing' axes, or any estimation caveats.

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?

Two short sentences with zero padding; the core comparison is front-loaded ahead of the detail about which inputs are considered.

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 an output schema present and annotations covering the read-only/idempotent profile, the description need not explain return values. It covers what is compared and which inputs matter, leaving only the sibling routing and clearance reliability unaddressed.

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 83%, so the schema already documents dimensions, units, the 'has'/'needs' connection strings and the accepted-subset behavior. The description's mention of dimensions and connections largely restates the schema and adds no new syntax or format detail.

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 a specific verb+resource: a fit check that 'compares dimensions plus typical installation clearances and required connections (power, water, gas)'. That scope is clear and separable from siblings like check_compatibility, though it never names the alternative, so an agent must infer the boundary itself.

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?

Usage is implied by the rhetorical question 'Will this appliance physically fit this space?', which tells the agent when the tool is relevant. It gives no when-not guidance and does not mention how it differs from check_compatibility or check_cart_before_checkout, both of which an agent might otherwise pick.

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