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

Annotations already provide readOnlyHint=true. The description adds meaningful behavior: it accepts Unix seconds/ms or ISO strings, omitting input means 'now', and output includes ISO, Unix, and human-readable forms. It does not contradict annotations and provides useful context beyond the structured fields.

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 with no filler. It front-loads the primary purpose and then efficiently explains input handling and rationale. Every sentence earns its place.

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?

The tool is simple, and a full output schema exists. The description covers purpose, input formats, timezone behavior, and usage rationale. No significant gaps remain for an agent to select and invoke the tool correctly.

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 baseline is 3. The description repeats that input can be a Unix timestamp or ISO string and mentions the IANA timezone, but it does not add meaning beyond what the schema already provides for each parameter.

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 the tool gets the current date/time or converts a given timestamp into a target IANA timezone, with ISO, Unix, and human-readable forms. It uses specific verbs ('get', 'convert') and specifies the resource (date/time, timestamp, timezone), making it distinct from all sibling tools.

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 explicitly says 'LLMs cannot know the real current time, so use this instead of guessing', giving a clear when-to-use scenario. It does not name alternatives or exclusions, but no sibling tool offers similar date/time functionality, so the context is sufficient.

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