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

With no annotations, the description carries the full burden and does add real behavioral context: the algorithm (NOAA solar equations), the accuracy bound (~1 minute), and the cost/auth model ($0.01/call in USDC on eip155:8453). It doesn't state what timezone returned times are in or whether calls are deterministic, but the accuracy and pricing disclosures are genuinely useful for planning a call.

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-loaded with the capability, and the pricing sentence earns its place. But the middle sentence duplicates the first ("use this when an agent needs...sun times") and contains a grammar error, so roughly a quarter of the text is dead weight.

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?

There is no output schema, so the description usefully previews the return fields (the list of computed sun times) and discloses cost. The remaining gap is timezone semantics for the returned times and the expected date string format — meaningful for a time-of-day tool, but not fatal given the accuracy claim and field list.

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 nominally 100%, so the baseline is 3, and the description adds the semigroup of lat/lon/date as free-form inputs rather than fixed locations. However, the schema descriptions are bare tokens ("Date"), and the description does not resolve the important ambiguity of date format/timezone, which materially affects sunrise/sunset output.

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?

Concrete verb (compute) plus an unusually specific output enumeration: sunrise, sunset, solar noon, civil dawn/dusk, golden hours, day length. An agent knows exactly what this returns, and the mention of lat/lon/date scoping separates it from pure calculators. It stops short of naming its closest sibling (geo_time_sun_position) to draw the line between sun times and sun position.

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?

"Use this when an agent needs to sun times, golden hour and day length for any place" gives an implied use case but is largely a restatement of the purpose sentence (and is grammatically broken). No when-not guidance and no routing to geo_time_sun_position for sun position/azimuth needs, which is the main adjacent tool.

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