current_date_and_time

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

With no annotations, the description carries the full transparency burden. It discloses the return type (str), a concrete example ('Today is Wednesday, 2026-09-23T13:02 (Swiss time)'), and the ISO 8601 without-offset format, noting it can be sent directly to the forecast tools. Minor gaps remain about edge cases like DST or system-clock dependence, but they are low-risk.

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 four concise sentences, each earning its place: purpose, usage timing, format rationale, and return example. It is front-loaded with the essential 'what' and keeps the supporting reasoning tight.

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-parameter utility tool, the description is complete. It covers what it returns, when to call it, how the output should be interpreted, and how it feeds into sibling forecast tools. Nothing needed to invoke it correctly is left out.

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?

The tool has zero parameters, so the baseline is 4. The description correctly avoids inventing parameter details and instead focuses on the returned value and its use. No further parameter documentation is needed.

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 opens with a clear verb and object: 'Get the current weekday and Swiss local time.' This unambiguously defines the tool's purpose. It also differentiates from the weather-forecast siblings by being the date/time anchor tool rather than a forecast tool.

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 explicitly tells the agent when to call it: 'Call this first when the question is relative, such as "tomorrow" or "tonight"'. It also explains why, saying the forecast tools expect a real date rather than an offset. This provides concrete, actionable routing guidance.

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