current_time

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

No annotations are supplied, so the description carries the full burden, and it does most of the work: it enumerates the returned payload (date, 24h time, weekday in English and Japanese, offset, UTC, epoch) and even surfaces a secondary use as a clock check on the server. It never states the operation is a safe read, but for a time query that is self-evident.

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 what it returns, then the routing advice, then the return payload — a sensible order with no filler. The return-field enumeration is slightly listy but each item is informative, so nothing is clearly wasteful.

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?

There is no output schema and no annotations, so the description takes on both jobs and does so: it lists the return fields and justifies the tool's existence versus computing the date locally. Nothing an agent needs to call it correctly is 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 0% for the single timezone parameter, so the description must compensate; it names the expected identifier format ('IANA') and gives a concrete example ('Asia/Tokyo'). The UTC default is left to the schema, which is a minor omission given only one 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?

States a specific verb+resource ('current date, time and weekday') and scopes it to 'an IANA timezone'. It is unmistakably distinct from every sibling (dnssec_check, ping_host, traceroute_path, etc.), so the agent can route between them without reading schemas.

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?

Explicitly tells the agent to prefer this over self-computed calendar arithmetic, and explains why ('it fails silently'), which is real when-to-use guidance. It stops short of stating edge cases such as what happens if the server clock is wrong or which timezone to pick by default, so not a full 5.

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