time_day_of_week

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

Annotations already indicate readOnlyHint=true and destructiveHint=false. The description adds valuable context: 'Pure local computation: read-only, non-destructive, contacts no external service, rate-limited (60 requests/minute)'. It also mentions strict validation and BCE support, fully disclosing behavior without contradicting 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 concise (5-6 sentences) and well-structured: purpose first, then mode explanation, then differentiation, then constraints, then safety/performance. Every sentence provides unique value, no redundancy.

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 (three modes, 11 parameters), excellent annotations, and an output schema, the description covers all necessary aspects: inputs, modes, constraints, safety, rate limits, and return metadata. No gaps remain.

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 coverage is 100% with descriptions for all 11 parameters. The description goes further by explaining the operation enum and how parameters relate to each mode (e.g., count for scan mode, fromYear/toYear for distance). This adds meaningful semantic context beyond the schema, justifying a slightly above-baseline score.

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 labels the tool as a 'Day of Week Calculator' and explains three distinct modes (weekday, scan, distance) with specific verbs like 'Find', 'list', and 'measure'. It distinguishes from sibling tool time_date_difference by specifying when to use each, ensuring no ambiguity.

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 ('weekday lookups and recurring weekday schedules') and when to use the alternative time_date_difference ('business-day counts or to add/subtract a duration'), providing clear, actionable guidance.

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