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

No annotations are provided, so the description carries the full burden. It usefully discloses cost and payment rail ($0.01/call, USDC, eip155:8453) and, since there is no output schema, the WHO category and healthy-range return values. It says nothing about validation, unit errors, or edge cases (e.g., zero/negative height).

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 first sentence is well front-loaded and earns its place, but the second sentence is garbled filler that duplicates the purpose, and the pricing clause is tacked on mid-sentence rather than structured separately.

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 calculation tool with no output schema, the description covers inputs, returned values, and cost. Only the broken usage sentence and absent validation/error context keep it from being fully 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 both parameters ('Height (cm)', 'Weight (kg)') are documented there. The description repeats the same unit semantics without adding format, range, or boundary detail, so 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 and resource ('Calculate Body Mass Index') plus the inputs and derived outputs ('WHO weight category', 'healthy BMI weight range'). This is clearly distinguishable from siblings like calculators_age_calculator or calculators_compound_interest_calculator.

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 second sentence ('Use this when an agent needs to body Mass Index with WHO category') attempts a when-to-use clause but is a broken, garbled restatement of the purpose rather than real guidance. No alternatives, no exclusions, no preconditions are offered.

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