time_week_number

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

Annotations already declare readOnlyHint, destructiveHint, and idempotentHint. The description adds significant value by stating it is 'pure deterministic week-numbering over UTC with no clock/now dependency', 'Read-only, non-destructive, idempotent, offline-capable, rate-limited (60 req/min anonymous), no auth.' It also explains the four week-numbering schemes in detail, which is well beyond annotations.

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 fairly long but well-structured, front-loading the purpose and then detailing each operation. It includes usage guidelines and behavioral traits. Every sentence adds value, though it could be slightly more concise. Still, it is well-organized and clear.

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 complexity of the tool (4 operations, 4 schemes, 6 parameters) and the presence of an output schema, the description combined with the schema is complete. The description covers all operations and schemes, and the schema provides full parameter details. The rule allows that output schema need not explain return values.

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%, so baseline is 3. The description provides high-level operation summaries (e.g., what each operation needs) but does not add significant per-parameter meaning beyond what the schema already provides. The schema descriptions themselves are thorough, so the description adds marginal value.

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 is a 'Week Number Calculator' and lists four specific operations (fromDate, toDate, weeksInYear, weekRange) with detailed explanations of each. It also distinguishes from sibling tools time_day_of_week and time_date_calculator by specifying their different use cases.

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 explicitly states when to use this tool: 'Use this for ISO week numbers or week-to-date conversion' and when not to use: 'use time_day_of_week for the weekday name of a date and time_date_calculator for adding/subtracting durations or business days.' This provides clear guidance on alternatives.

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