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

With no annotations, the description carries the full burden and usefully discloses that the tool handles midnight sun and polar night. It also describes the returned sun-time concepts, though it does not explicitly state read-only behavior or response formatting.

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 compact and front-loads the returned values before adding edge-case handling and the alternative-tool note. Every sentence contributes useful selection context.

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?

The definition is nearly complete for a read-only sun-times tool with full schema coverage and no output schema: it lists outputs, edge cases, and a key alternative. The main omission is that the description itself does not mention the important timezone recommendation, though the schema does.

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 lat, lon, date, and timezone are already documented in the schema. The description adds only the high-level notion of 'location and date' and does not add syntax or timezone guidance beyond the schema.

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 names the exact resource and outputs: sunrise, sunset, solar noon, civil dawn/dusk, golden hour, and day length for a location and date. It also distinguishes the tool from vitamin D-oriented siblings, so an agent can identify its purpose without opening the schema.

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?

It explicitly says to use the vitamin_d tools for vitamin D questions, which is a clear usage exclusion. However, it does not distinguish this tool from nearby sun-related siblings such as get_sun_forecast or estimate_sun_session.

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