Prayer times

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

Annotations already cover read-only/idempotent/no-destruction, so the description's added value is the operational constraints: Iran local time, 24-hour format, today-only restriction that produces an error, and the province dependency. It does not discuss caching or rate limits, but for a pure lookup those are minor.

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?

Three short sentences: purpose and return fields first, then formatting, then the two blocking constraints. No filler, and the error-producing constraint is placed prominently.

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?

With no output schema, the description supplies the return field list itself, plus format (24h, local time) and the failure conditions an agent must avoid. Nothing material is missing for a four-parameter lookup tool.

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%, so the baseline is 3; the description earns above that by adding meaning the schema lacks — that `date` is effectively pinned to today and that `province` is mandatory for non-capital cities. It repeats the schema's province note but adds the hard 'today only' semantic.

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?

Specific verb ('Get') plus specific resource ('Islamic prayer times') scoped to an Iranian city and day, with the returned fields (fajr, sunrise, noon, sunset, maghrib, Islamic midnight) enumerated. That enumeration also distinguishes it from siblings like ti_qibla (direction) or ti_today (date info).

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 concrete preconditions: only today is supported (any other `date` errors) and non-capital cities require `province`. That is real when-to-use guidance, though it never explicitly routes to or away from a sibling tool.

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