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

With no annotations provided, the description carries the full burden of behavioral disclosure. It fails to mention what happens with an invalid zone, the format of the returned time, or that the tool only uses the 'zone' parameter while ignoring the other eight schema parameters. The schema descriptions for other parameters say 'discarded after the shape check,' but the tool description does not clarify that only zone matters, leaving potential confusion.

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 sentence with zero waste. It is front-loaded with the essential information and does not include any redundant details. This is optimal conciseness.

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 has 9 parameters, but the description only addresses one (zone) and does not explain the purpose of the other eight, which are described as discarded or checked. This mismatch is confusing. Additionally, there are several sibling time tools (utc-time, iana-zones, tz-asia-tashkent) and the description does not explain how to choose among them or handle edge cases like invalid zones. The description is insufficient for an agent to use the tool correctly in all contexts.

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% with each parameter described. The description adds no new semantic value beyond what the schema already provides for 'zone' (IANA timezone name). The description's mention of 'named IANA timezone' aligns with the schema but does not enrich it. Baseline 3 is appropriate given the high schema coverage.

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's function: 'Current time in a named IANA timezone.' It specifies the verb (get current time), resource (time), and scope (named IANA timezone), which distinguishes it from siblings like utc-time (likely UTC-specific) and tz-asia-tashkent (a specific zone). The purpose is unambiguous and well-scoped.

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 gives no guidance on when to use this tool versus alternatives. It does not mention utc-time, iana-zones, or any other sibling, nor does it state any prerequisites or exclusion criteria. An agent would have to infer usage from the description alone, which is not explicit.

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