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

With no annotations, the description carries the full burden of behavioral disclosure. It does not mention that only the 'zone' parameter is used, nor does it disclose that other parameters (ref, url, city, etc.) are discarded or ignored. This is a significant omission given the schema lists 9 parameters, many seemingly unrelated to timezone lookups. The description provides no insight into parameter handling or potential side effects.

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, extremely concise and front-loaded with the core purpose. However, it may be too terse—it sacrifices critical context about parameter usage, making it less helpful than a slightly longer description that clarifies which parameters matter.

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?

Given the tool has 9 parameters, many unrelated to timezone, and no output schema, the description is insufficiently complete. It fails to indicate that only 'zone' is relevant, leaving the agent to guess about the purpose of other parameters. For a simple tool this could be acceptable, but the schema's noise creates a completeness gap that the description should address.

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?

The schema descriptions cover 100% of parameters, so the baseline is 3. The description adds no extra meaning beyond the schema, but the schema itself is confusing because it includes many parameters unrelated to timezones. The description's mention of 'named IANA timezone' implies 'zone' is the key parameter, but it doesn't clarify the role of the others. Since the schema does the heavy lifting, a 3 is appropriate.

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 'Current time in a named IANA timezone' uses a specific verb (current time) and resource (named IANA timezone), clearly distinguishing it from sibling tools like utc-time and iana-zones. The purpose is unambiguous.

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 implies usage (call with a timezone name) but does not explicitly state when to use this tool over alternatives like utc-time or iana-zones. No exclusions or alternative routing is provided, leaving the agent to infer based on the name and description.

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