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

No annotations exist, so the description carries the full burden of disclosing behavior, but it reveals nothing: it does not state that all inputs are accepted and ignored, that no side effects occur, or that the parameter list is a shape-check artifact rather than meaningful configuration. The schema's per-parameter "discarded" notes hint at this, but the tool-level description should state the quirk plainly.

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?

A single three-word sentence is maximally concise and front-loaded with the purpose. However, it is under-specified relative to the tool's actual interface: for a tool carrying a 9-parameter schema with discard semantics, this brevity crosses from conciseness into incompleteness. It earns its place but is not appropriately sized for the surrounding complexity.

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 zero-required-parameter tool with no output schema, a complete definition is easy: say it returns the UTC timestamp and all inputs are ignored. Instead, an agent must inspect all nine schema entries to infer the discard behavior and still cannot be certain whether zone or ref affect the result. The description leaves the tool's true contract ambiguous.

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. Each parameter has its own explanation (e.g., "Git ref name; discarded after the shape check"), which the description doesn't need to duplicate. However, the description does nothing to reconcile why a UTC-time tool accepts a weather city or a JSON payload, leaving a semantic gap that the schema alone cannot resolve.

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?

"Current UTC timestamp" clearly states the tool's function: return the current UTC time. It is a specific resource with a precise output, and the semantics distinguish it from the sibling tool "timezone," which implies zone handling or conversion. It is not a tautology and leaves little doubt about the core operation.

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 offers no guidance on when to use this tool versus alternatives like timezone, nor does it warn that all 9 parameters are optional and discarded. Given the confusingly broad input schema (url, city, feed, json, path, zone, query), an agent receives zero help deciding whether to pass anything or how this differs from sibling time/validation tools.

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