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

The tool has readOnlyHint=true and idempotentHint=true, meaning it is a safe read operation. The description adds that it calculates specific times and supports two modes (coordinates or city), which is useful context beyond annotations. It does not mention rate limits or error conditions, but the annotations already cover the safety profile, so this is not a major gap.

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, information-dense sentence that conveys all essential information without redundancy. It front-loads the main purpose and includes both usage modes, making it efficient and well-structured.

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 that the schema covers all parameters and there is no output schema, the description provides enough context for an agent to call the tool correctly. It explains the inputs and what is calculated, and the annotations confirm safety. A slight gap is not mentioning the output format, but that is not required since there is no output schema.

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?

The schema description coverage is 100%, meaning all parameters are described in the schema. The description adds that the city slug supplies coordinates, timezone, and suggested method, which is useful for understanding how city and coordinates interact. However, it does not provide additional semantics beyond what the schema already explains, so 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?

The description clearly states the tool calculates five daily prayer times plus additional times (sunrise, imsak, midnight, last third) for either coordinates or a city slug on a given date. It uses specific verbs and resources, making it distinct from siblings like get_qibla or list_prayer_cities.

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 implies that you can use either coordinates or a city slug, and that city slug is preferred when available. However, it does not explicitly state when to use this tool over siblings, such as for qibla direction or city lists, but the context is clear enough.

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