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 conveys that this is a read-only time lookup with no obvious side effects, but it does not describe the output format or clarify that the tz value is actually used rather than discarded. Core behavior is clear, but additional transparency is thin.

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. It communicates the essential operation efficiently and is appropriately sized for a simple lookup tool.

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, leaving the return format and safety profile implicit. With nine optional parameters in the schema, the description does not explicitly say that only tz is relevant, which introduces some ambiguity. The core purpose is well covered, but the description alone is not fully self-sufficient.

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% and the schema already documents the tz parameter as 'IANA zone name'. The description connects that parameter to the tool's purpose by referring to a 'named IANA timezone', making it clear that tz selects the zone for which time is returned. The parameter name is not explicitly repeated, but the mapping is unambiguous.

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 states a specific operation: return the current time for a named IANA timezone. The phrase 'named IANA timezone' clearly distinguishes it from siblings like utc-time and iana-zones. There is no tautology or ambiguity.

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 the tool: when the caller needs the current time in a specific IANA timezone. However, it does not explicitly name alternatives, exclusions, or when-not-to-use conditions, leaving the usage guidance largely implicit.

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