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

With no annotations, the description carries the full burden, but it only states the result and does not disclose behavior for invalid zone names, return format, or whether the extra url/host/json parameters affect execution. No side effects are mentioned, leaving important behavioral details unspecified.

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 concise sentence with the key information front-loaded. There is no unnecessary verbosity.

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 description omits return format and does not address the unrelated parameters in the schema. Since there is no output schema, the description should at least state what form the current time takes, and it should reconcile the extra parameters; it does neither.

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 contains four parameters, but only zone matches the tool description; url, host, and json have descriptions unrelated to timezone (normalize/cite, hostname, validate JSON). The tool description does not clarify their relevance or indicate that they are ignored, so parameter semantics are actively misleading.

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' clearly identifies the tool's purpose and distinguishes it from sibling utc-time (UTC time) and iana-zones (timezone lists). The verb and resource are specific enough for an agent to select this tool.

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 when to use it (when a named IANA timezone's current time is needed) but does not explicitly mention alternatives or exclusions such as utc-time for UTC or iana-zones for list operations. Usage guidance is only implicit through the tool name and description.

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