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

With no annotations, the description is the only behavioral disclosure, and it does convey the core read-only behavior. However, it does not mention output format, invalid-zone behavior, or that the other schema fields appear unrelated, so transparency is only adequate.

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. Every word contributes to identifying the tool's purpose.

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?

For a simple time lookup, the core input (zone) and purpose are stated, making the definition minimally viable. But with no output schema, no annotations, and a schema that includes unrelated optional parameters, the description is not rich enough to fully clarify expected output or call pattern.

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 description coverage is 100%, so the baseline is 3. The description reinforces zone as the IANA-name parameter but adds no clarity about the three unrelated optional parameters (url, host, json), leaving the agent without guidance on whether they are 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 clearly identifies the operation as reporting the current time in a named IANA timezone. This is enough to separate it from iana-zones and utc-time, though it does not explicitly differentiate it from rfc3339-now.

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 the tool is for current-time lookups by IANA zone, but it gives no explicit when-to-use or when-not-to-use guidance. An agent must infer the boundary against sibling tools like utc-time and rfc3339-now.

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