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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds that computation is sidereal and lists the output payload, and the metadata discloses a 20-credit (Tier 2) cost, which is real value beyond annotations; however it says nothing about rate limits, ayanamsa defaults, or timezone requirements.

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?

Two tight sentences front-load the calculation and the return payload, followed by a compact metadata block. Nothing is padded or redundant, though the bracketed lines are somewhat boilerplate.

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?

An output schema exists, so explaining return values is not strictly required, and required inputs plus cost are supplied. For a 15-parameter calculation with 33% schema coverage, however, the description leaves notable gaps around the sidereal configuration options and timezone handling that an agent would need to resolve elsewhere.

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 only 33% across 15 parameters, so the description should compensate more than it does. It does name the four required inputs and pins the zodiac mode to sidereal, which is useful, but it says nothing about the compact-mode fields, ayanamsa school selection, or the timezone/timezoneOffset interplay, leaving that burden entirely to 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 gives a specific verb and resource ('Calculate the Nakshatra (lunar mansion) for each planet using the sidereal zodiac') and even names the returned fields. The 'for each planet' scope implicitly separates it from the per-day sibling astroway_vedic_panchang_nakshatra_of_day, but that sibling is never named, so differentiation is left to inference.

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?

There is no statement of when to choose this tool over the many other Vedic calculation siblings, and no prerequisites or exclusions. The bracketed metadata lists required inputs and credit cost, which is practical context, but that is not usage guidance about when the tool is the right call.

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