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

With no annotations, the description carries the full burden of explaining behavior, but it only states the basic operation. It does not disclose the response format, error behavior for invalid timezone names, or whether the returned time is local time, UTC offset, or an ISO timestamp.

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 a single, front-loaded sentence with no filler. Every word contributes meaning, and it is immediately scannable for an agent.

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 read-only time lookup, the description conveys the core function, but it leaves gaps: it never names the zone parameter explicitly, does not describe the output format, and does not account for the three extraneous schema properties. The lack of an output schema and annotations makes these gaps more significant.

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 zone parameter's schema description ('IANA timezone name') aligns with the tool description, but the schema also includes unrelated parameters (url, host, json) with no clarification that they are irrelevant to this tool.

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 identifies the tool's purpose: returning the current time for a named IANA timezone. It effectively distinguishes this from sibling tools like utc-time and iana-zones, though it lacks an explicit verb such as 'get' or 'return'.

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 phrase 'named IANA timezone' implies the tool should be used when a caller has a specific IANA timezone name and needs its current time. However, it does not explicitly state when not to use it or mention alternatives like utc-time for UTC-only needs.

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