get_datetime_info

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

With no annotations, the description carries the full burden, and it does: it discloses that everything defaults to now, that a reference date enables a signed day/second delta, and that multiple timezone representations are produced for the same instant. It doesn't discuss error behavior when an input form is unparseable, but the tool is a transparent read-only computation.

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?

Front-loaded with purpose, then defaults, then result fields, then accepted formats – a sensible order with no filler sentences. The long field enumeration is dense but each item is informational rather than padding.

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?

An output schema exists, yet the description still enumerates key fields, which is mildly redundant but helps the agent decide to call it. Inputs, defaults, comparison semantics, and accepted formats are all present; only sibling routing and parse-failure behavior are missing.

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 coverage is 100%, so baseline would be 3, but the description adds real value the schema lacks: a concrete list of accepted datetime input formats (ISO, slash-separated, Japanese kanji form, era notations like '令和6年12月10日' and 'R6.12.10', and time-only meaning today). That format guidance is the main practical risk of mis-calling the tool and it is covered.

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 opens with a specific verb and resource ('Get details of a date-time') and then enumerates the exact fields returned (ISO, timezone, wareki, ISO week, quarter, diff from reference), making the scope unambiguous. It doesn't explicitly name the siblings get_datetime/convert_time/shift_datetime, so differentiation is implied by the inspection framing rather than stated.

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?

It states the useful defaults (omit for now, reference defaults to now) and gives a concrete use case ('how many days until a date'), which implies when to call it. It never says when to prefer it over convert_time or shift_datetime, so the agent must infer the boundary from sibling names alone.

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