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 only says 'Current time', omitting details like return format, error handling for invalid zones, whether it makes network requests, or if it is read-only. The presence of unrelated parameters (url, host, json) is unexplained, which could confuse agents.

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 that directly conveys the tool's purpose with no unnecessary words. It is front-loaded with the core action and resource.

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 is too sparse for a tool with four parameters and no output schema. It fails to specify what the tool returns (format, structure), the relevance of the url, host, and json parameters, or any error behavior. This incompleteness could lead to incorrect invocation or misunderstanding.

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 all four parameters have descriptions. The description adds marginal value by implying that the zone parameter is the key input, but it does not clarify the purpose of url, host, or json in the context of a timezone tool. Baseline 3 is appropriate since the schema already documents parameters.

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 purpose: returning the current time for a named IANA timezone. It distinguishes itself from siblings like utc-time (which presumably gives UTC time) and iana-zones (which lists zones), making it easy to select for timezone-specific queries.

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?

No guidance is provided on when to use this tool versus alternatives. The description does not mention utc-time or iana-zones, nor does it specify contexts where this tool is preferred. An agent must infer usage solely from the name and purpose.

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