util_weekday

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

With no annotations, the description should disclose all behavioral traits. It mentions timezone awareness, which is good, but it does not specify what happens with invalid input, missing parameters, or edge cases. For a simple tool, minimal disclosure is provided.

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, concise sentence that conveys the core functionality without any fluff. Every word is meaningful and 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?

The description does not explain the return value or format (e.g., string like 'Monday' or number). Given the absence of an output schema, this information is missing, making the tool incomplete for an agent without prior knowledge.

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 schema already describes both parameters (timezone and date) with brief descriptions. The description adds the context of timezone awareness, but does not elaborate on expected formats or constraints beyond what's in the schema. With 100% schema coverage, baseline 3 is appropriate.

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's purpose: determine the day of the week with timezone awareness. It uses specific verb+resource and distinguishes from sibling utility tools that perform other calculations.

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 gives no explicit when-to-use or when-not-to-use guidance. Since there are no competing weekday tools, the context is implied, but the description does not help the agent decide when to invoke this tool over others.

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