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

No annotations are provided, so the description carries the transparency burden. It correctly implies a read-only lookup by describing 'current time,' but it does not disclose return format, invalid-timezone behavior, or that unrelated schema parameters are ignored. This is adequate but not richly transparent.

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 that communicates the core purpose with no filler. Every word earns its place, and the structure is easy to parse.

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 definition is minimally workable: the description states the output and the schema documents all parameters. However, with no output schema, no annotations, and a schema containing many apparently unrelated parameters, the description should clarify that only the 'zone' parameter is relevant and could mention output format or alternative tools. This leaves clear gaps.

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%, so each parameter is already described, including 'zone' with an example. The description adds no parameter detail beyond the phrase 'named IANA timezone,' which is essentially the same as the schema's own description. Baseline 3 is appropriate because the schema carries the parameter documentation.

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: returning the current time for a named IANA timezone. It implies the core input and is distinguishable from sibling tools like utc-time and iana-zones, though it does not explicitly name those alternatives.

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?

Usage is implied rather than stated: an agent would use this when it needs the current time in a specific IANA timezone. There is no explicit guidance about alternatives, exclusions, or when not to use this tool, so the guidance is only moderately helpful.

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