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

Goes well beyond annotations by disclosing that the engine is deterministic ('no AI inside'), that 'nothing logged', which Hijri convention is used (Umm al-Qura), and what precision/language/relative-base metadata is returned. These are non-obvious behavioral traits an agent would otherwise not know.

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?

Front-loads the core purpose with examples, then covers params and response shape. It is dense and packs several ideas into one paragraph, but virtually every clause carries information; minor trimming of the fully-duplicated example would help.

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 6-param tool with an output schema and full annotation coverage, the description supplies everything needed: input formats, when to pass hints, determinism/privacy behavior, and a sketch of the response. Nothing an agent needs to call it correctly is missing.

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 parameters are already well documented. The description adds only mild value by echoing 'Pass languages and date_order when known' and noting relative base is reported, but adds no syntax or format detail beyond the schema. Baseline 3 is appropriate.

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?

States a specific verb and resource ('Turn a date written in natural language... into an ISO date/datetime') with concrete multilingual examples including Hijri. This clearly separates it from numeric siblings like parse_number or convert_digits.

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?

Gives actionable guidance ('Pass languages and date_order when known') and implies the tool's context via examples. However, it never explicitly contrasts with siblings or states when NOT to use it (e.g., for pure numbers), leaving some inference to the agent.

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