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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is fully covered. The description adds the local-midnight-to-midnight day boundary and the fact that each planetary hour is listed together with overlapping void-of-course periods, but it says nothing about pagination, size limits, or error behavior beyond the external docs link. Useful scope context, but not rich behavioral disclosure.

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?

Content is front-loaded: a one-sentence purpose, then labeled WORKFLOW, INPUT CONTRACT, and DO NOT CONFUSE WITH blocks that are easy to scan. Slightly over-formatted, and the input contract line duplicates structured schema data rather than adding to it.

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 an output schema present, return values need no explanation, and annotations carry the safety profile; the description supplies scope, workflow positioning, and the key sibling disambiguation plus a docs link for the full contract. The only gap is that it does not clarify why an agent should use this aggregate day view instead of the overlapping planetary-hours or void-of-course siblings.

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 the nested location object (date, lat, lon, timezone, response_format) is already documented in structured form. The description's "INPUT CONTRACT" line merely restates those same fields without adding format rules, defaults, or constraints beyond the schema, so the baseline of 3 applies.

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?

Specifies the exact scope ("One calendar day at a place, Western style") and enumerates the concrete contents returned: planetary hours, void-of-course Moon periods, Moon sign changes, and Moon phase. It also names a specific sibling it must not be confused with (asterwise_get_panchanga), so an agent can identify the tool 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?

Explicitly states the tool is standalone ("BEFORE: None") and names the natural follow-up tool (asterwise_get_western_daily_factors) for the personal picture on the same day. It lacks guidance on when to prefer this composite day view over the narrower siblings like get_western_planetary_hours or get_western_void_of_course_moon, which is a real usage gap.

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