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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 does reveal the return contents and the tool's authoritative role, but it does not cover error behavior, timezone validity, or what happens with different calendar options. The phrase 'deterministic time' is also slightly confusing given that current time changes, which undermines transparency.

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 only three sentences, with the purpose and usage rule front-loaded. Every sentence adds value: purpose, call-don't-infer rule, and return fields. There is no redundancy or filler.

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 simple tool with zero required parameters and a fully documented schema, the description provides the essential output fields and usage rule. It is slightly incomplete because it does not state output formatting or how timezone/calendar parameters affect the result, but given the low complexity, the gap is minor.

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%, with both parameters (calendar and timezone) already documented meaningfully in the schema. The description adds nothing about the parameters themselves, so the baseline of 3 applies.

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 returns the current deterministic time and enumerates the exact output fields (UTC and local time, weekday, UTC offset, DST status). It is specific and unambiguous about the resource and verb, but it does not explicitly differentiate itself from sibling tools such as convert_time or timezone_info, so it misses the top score.

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 instruction 'Do NOT let the LLM infer the current date/time — call this tool instead' is a strong, explicit usage guideline that tells the agent when to invoke this tool. However, it does not mention alternatives or conditions for when to choose a sibling tool, so it lacks the explicit routing that would earn a 5.

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