get_current_datetime

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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds genuinely useful context the annotations cannot — that this value supersedes the model's training cutoff when interpreting relative terms. It does not discuss precision or call cost, which is acceptable given the output schema exists.

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?

Two short sentences, zero waste, with the operational directive placed after the core purpose in a natural read order. Every clause earns its place.

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?

A trivial zero-param read tool with an output schema, so return values need no explanation. The one thing an agent could get wrong — assuming its own date is current — is addressed directly.

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?

Zero parameters, so the baseline is 4 by rule. The description correctly implies a no-argument call requiring no input context.

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?

States a specific verb and resource ('Return the current date and time in UTC') with the timezone scope made explicit. No sibling tool overlaps with this function, so ambiguity is effectively zero.

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?

Explicitly instructs 'Call this first' and explains exactly why: 'latest' and 'recent' in sibling tools are relative to this date, not the agent's training data. This is a clear when-to-use directive tied to real sibling behavior rather than generic advice.

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