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

The annotations (readOnlyHint=true, destructiveHint=false, openWorldHint=false) already establish this as a safe, closed computation, so the description's formulas add little behavioral context. It does not disclose the important behavior that inputs are optional and the tool can be expected to solve for missing values (e.g., deriving base from area and height), which is the key thing an agent needs to know.

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?

It is a single terse sentence with no filler, and the formulas are front-loaded. Its brevity is efficient, though it comes at the cost of not stating the tool's purpose explicitly.

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 five-parameter, zero-required-parameter calculator, the description is too thin: it never explains that any subset of dimensions can be supplied or how the 'calculation' selector interacts with the inputs. The output schema and annotations cover the result format and safety profile, but the invocation logic remains undocumented.

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%, so the schema already documents all five parameters, and the description's mention of base, height, and side merely echoes three of them. It adds no meaning about the 'calculation' enum (area|perimeter|all) or about how supplying 'area' changes the calculation.

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 gives the two formulas (area = base×height, perimeter = 2(base+side)), which implies it computes parallelogram area and perimeter. But there is no explicit verb or statement of what the tool does, and nothing distinguishes it from nearby siblings like calculator_rectangle or calculator_trapezoid beyond the formula names.

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?

There is no guidance on when to use this tool versus the many other geometry calculators, nor on which parameter combinations are valid. The schema permits zero required parameters and includes a 'calculation' selector, but the description never says how to choose inputs.

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