calculate_day_of_week

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

With no annotations, the description must carry the burden. It implies a read-only calculation and mentions the algorithm, but it does not explicitly state the absence of side effects or any constraints like valid date ranges.

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 three sentences long, front-loading the purpose and usage. The third sentence about list_bundles is slightly extraneous but not harmful.

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, the description covers purpose, usage, and return type. However, the parameter contradiction undermines completeness, and it lacks explicit mention of output format or error behavior.

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 description says 'Inputs: day, month, year' which contradicts the actual schema, which has a single 'date' parameter in YYYY-MM-DD format. This mislead the agent about the input structure, despite the schema being well-documented.

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 it finds the day of the week for any date using Zeller's congruence, and provides examples like historical dates or birthday checks, distinguishing it from other date calculators in the sibling list.

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 advises using it for historical dates or birthday checks, giving clear context for use, though it does not explicitly state when not to use the tool or provide alternatives.

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