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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds real value beyond that by disclosing what the answer contains (rule of thumb, sofa type, clearances, door-fit dimension) and noting that a linked page carries the sources.

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 core output — the two-thirds rule — is front-loaded, and there is no filler. The phrase 'largest smallest-dimension' is awkward and slightly opaque, which is the only drag on clarity.

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 two-parameter, side-effect-free calculator with no output schema, the description covers what is computed, the heuristic behind it, and what the answer includes. The only gap is that it gives no sense of edge-case behavior, such as when a wall is too small or a door too narrow.

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 both parameters (wall in feet, door width in inches) are already documented. The description reinforces why door width matters (door clearance for delivery) but adds no format, range, or edge-case detail beyond the schema, so the baseline of 3 applies.

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 a concrete resource (a sofa against a wall) and the specific outputs: recommended length, sofa type, clearances, and the maximum dimension that fits through a door. The resource makes it clearly distinct from siblings like rug_size or coffee_table_size, though it never explicitly contrasts with them.

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 resource — an agent needing a sofa length for a given wall would pick this. There is no explicit when-to-use, when-not-to-use, or named alternative, and nothing states prerequisites or limitations on the wall/door inputs.

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