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

With no annotations provided, the description must carry the full burden of behavioral disclosure. It mentions 'Calculation runs on smart-tools.xyz' but does not clarify whether the operation is read-only, whether data is stored, what the response format is, or any error handling. For a conversion tool, this is a significant transparency gap.

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 description is two sentences long and front-loaded with the main action, followed by a tidy list of units. Every sentence earns its place; there is no redundant or filler text.

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?

Given the absence of an output schema, the description fails to state what the tool returns or how the result is structured. It also lacks detail on precision, rounding, or behavior for invalid inputs. For a tool that an agent must invoke and interpret, this is incomplete.

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?

The input schema covers all four parameters with descriptions and enum constraints, so baseline is 3. The description adds full names for the unit abbreviations (e.g., 'Square kilometer'), but it does not explain the 'locale' parameter or provide additional semantic details. Schema already does the heavy lifting, so no higher score is warranted.

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 clearly states 'Convert a value between area units' with a specific verb and resource, and it enumerates the exact units supported. This distinguishes it from sibling converters (length, temperature, etc.) and leaves no ambiguity about its function.

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 description provides clear context by listing all supported area units, making it obvious when to use this tool versus other converters. It does not explicitly state when not to use it, but the unit scope implicitly serves as usage guidance.

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