date

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states the tool returns a day of the week but doesn't mention error handling (e.g., invalid date formats), default behavior (e.g., using system locale if unspecified), or output format (e.g., string like 'Monday' vs. numeric). This leaves significant gaps for a tool with parameters.

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, efficient sentence that front-loads the core functionality. There is no wasted text, making it appropriately concise for a simple tool.

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 moderate complexity (2 parameters, no output schema, no annotations), the description is incomplete. It lacks details on parameter usage, error cases, and output specifics, which are essential for reliable agent invocation. Without annotations or output schema, more descriptive context is needed.

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 0%, so the description must compensate for undocumented parameters. It mentions 'a given date or today,' which hints at the 'date' parameter but doesn't explain its format (e.g., ISO 8601) or optionality. The 'locale' parameter is entirely unmentioned, leaving its purpose and usage unclear.

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: 'Returns the day of the week for a given date or today.' It specifies the verb ('returns') and resource ('day of the week'), though it doesn't explicitly differentiate from sibling tools like 'format-date' or 'get-current-datetime' beyond the specific output focus.

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?

No guidance is provided on when to use this tool versus alternatives like 'format-date' (which might also output day of week) or 'get-current-datetime' (which provides broader datetime info). The description implies usage for date-to-weekday conversion but lacks explicit context or exclusions.

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