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. The one-line description only states the output ('Current time') and does not disclose that the other eight parameters are 'discarded after the shape check' as noted in the schema, nor does it mention any side effects, permissions, or response format. The description is silent on what happens if the zone is invalid or if other parameters are passed.

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 short sentence, which is concise, but it is under-specified given the tool's complexity (9 parameters, no output schema). It front-loads the core action but omits necessary context such as how the other parameters are treated and what the response looks like. The brevity is not effective conciseness; it is a lack of necessary 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?

This is a tool with 9 optional parameters, no required ones, no output schema, and a description that only explains the timezone aspect. The agent has no idea why the other parameters exist, what the response format is, or how to correctly invoke it. The description is grossly incomplete for the actual schema, making the tool effectively unusable without opening the schema and guessing.

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% - every parameter has a description, including the 'zone' parameter which is labeled 'IANA timezone name'. The tool description adds no additional meaning beyond the schema. Since the schema already provides full parameter documentation, the baseline of 3 applies; the description does not enhance or clarify parameter usage.

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 clear verb ('Current time') and resource ('named IANA timezone'), but the input schema contains 8 unrelated parameters (ref, url, city, feed, host, json, path, query) that suggest the tool actually performs generic shape-checking across many domains. This creates confusion about the true purpose and fails to distinguish it cleanly from sibling shape-check tools like domain-shape or github-repo-shape, despite the 'utc-time' sibling being a clear alternative.

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. For example, there is no mention that utc-time should be used for UTC or that this tool is only for named zones. The description offers no context, prerequisites, or exclusions, leaving the agent to infer usage from the name alone.

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