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

There are no annotations, so the description must carry the transparency burden. It mentions the default reference date but does not disclose the return format, the source_url link referenced by the locale parameter, or edge cases like date ordering and timezone handling. 'Runs on smart-tools.xyz' is vague and not a behavioral disclosure.

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 very short—two sentences—but the second sentence, 'Runs on smart-tools.xyz', does not earn its place as it adds no value for tool selection or invocation. It is efficient but contains filler, so it does not achieve a top conciseness score.

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 simple calculator, the core behavior is defined, but with no output schema and no explanation of the result's full composition (including any returned link), the description is not fully complete. It also does not address edge cases or differentiate among sibling calculators like date_difference_calculator, leaving gaps in context.

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 100% of parameters with descriptions, so the baseline is 3. The description adds no extra meaning beyond the schema—it repeats birth_date and the default for at_date (today), while the purpose of locale (affecting the source_url link) remains only in the schema and is not clarified in the description.

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?

Description states 'Exact age in years, months and days between a birth date and a reference date', clearly specifying the tool's function and output units. This distinguishes it from sibling tools like date_difference_calculator by focusing on birth-date-based age with a default reference date.

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 implies usage context: provide a birth date and optionally a reference date (defaulting to today). However, it does not explicitly state when to use this tool over alternatives like date_difference_calculator or due_date_calculator, nor does it provide exclusions or when-not-to-use guidance.

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