calculate_day_of_week

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

No annotations provided, so the description carries the full burden. It names the algorithm (Zeller's congruence), but does not disclose limitations such as calendar system (Gregorian only) or date range validity. Side effects are absent, but more depth would improve 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 very concise with two sentences. The first sentence immediately states the tool's purpose, and the second adds usage context. No wasted words.

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?

Given the tool's simplicity and the presence of an input schema, the description is mostly complete. It explains what it does, how to use it, and where to find related tools. Could mention the output format explicitly, but the 'returns weekday name' is sufficient.

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 input schema covers the 'date' parameter with format YYYY-MM-DD. The description adds that inputs are day, month, year and returns a weekday name, which is helpful but not essential. Schema coverage is 100%, so baseline is 3.

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 'Find the day of the week for any date' using Zeller's congruence, providing a specific verb and resource. It also mentions use cases like historical dates or birthday checks, distinguishing it from sibling calculators.

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 suggests use for historical dates or birthday checks and refers to list_bundles for related 'fun' calculators. While it provides context, it does not explicitly state when to avoid using this tool or mention alternatives.

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