area_calculate

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

Annotations already declare readOnly/idempotent/non-destructive, so safety is covered. The description adds one genuinely useful behavioral fact — perimeter is returned only 'where possible', i.e. output varies by shape — but says nothing about precision, units, or whether formulas/steps come back.

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?

A single sentence with zero filler, verb and scope front-loaded, and the shape list packed into a compact enumeration. Nothing to trim.

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 carry return-value burden; it says area plus optional perimeter but leaves the response shape, numeric precision, and unit assumptions unspecified. Adequate for a deterministic math tool, but not complete.

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 100% and each property already names the shape(s) it applies to (e.g. base1/base2 for trapezoid, angle_degrees for sector), so the schema carries the semantics. The description only adds that shape determines which parameters matter; baseline 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?

States a specific verb ('Calculate') and resource ('area ... of common shapes'), then enumerates the seven supported shapes, which lets an agent match a request to this tool rather than to convert_area or polygon_calculate. It never explicitly contrasts with those siblings, so it stops 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?

The enumerated shape list implies when to use it (a named shape with known dimensions), but there is no explicit when-not guidance and no pointer to alternatives such as triangle_solve (for missing sides/angles) or polygon_calculate (for irregular polygons). Usage must be inferred.

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