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

With no annotations, the description carries the full burden of disclosing behavior. It implies a read-only time lookup, but it does not mention that most schema parameters are unrelated or ignored, nor does it state any side effects or output behavior.

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 one-sentence description is concise, front-loaded, and free of filler. It states the essential purpose immediately without unnecessary detail.

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 nine optional parameters, no output schema, and no annotations, the description is too sparse. It does not specify which parameter to use, what happens when no zone is supplied, what the return format is, or why the other parameters exist.

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 the baseline is met, but the description adds no parameter-level meaning. The schema lists nine optional strings, many with descriptions like 'discarded after the shape check' or 'no disk access,' which are confusing for a timezone tool; only 'zone' is clearly relevant.

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 states the tool's core function and distinguishes it from sibling tools like utc-time and iana-zones. It does not explicitly name those alternatives, but the intended 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?

There is no guidance about when to choose this tool over alternatives, what inputs are expected, or what to do when the relevant parameter is omitted. The description provides only the core function and no usage context.

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