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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the description's job is lighter. It still adds real context: sizing comes from two manufacturers' charts plus a designer rule of thumb, and the answer links to sources, which tells the agent the result is advisory and provenance-backed rather than a single canonical formula.

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?

Front-loaded with the useful part: what gets computed from what. The trailing clause about the linked page earns its place as provenance, though the phrasing is slightly run-on and 'Gives the designer rule of thumb' could be folded more tightly into the first sentence.

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 no output schema, the description must telegraph the return values, and it does: a blade span plus a mount recommendation, with source citations. It stops short of naming the possible mount types or the unit of the returned span, which would close the last gap for a stateless read-only calculator.

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 all three parameters are already documented with units and the default of 8 feet for ceiling. The description adds only mild mapping value — floor area from length/width drives blade span, ceiling height drives mount — which is a modest gain over the schema. Baseline 3 applies when the schema carries the 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 names two concrete outputs — blade span suited to a room's floor area and the mount suited to ceiling height — so the agent knows exactly what the tool computes. The resource (ceiling fan sizing) is distinct from every sibling (chandelier_size, pendant_spacing, rug_size), so no ambiguity arises from the tool list.

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: call it when a room's length and width are known and a ceiling fan must be sized. There is no explicit statement of when not to use it, no mention that the room dimensions must be in feet for the answer to be meaningful, and no alternative named for cases like vaulted ceilings or non-rectangular rooms.

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