Nakshatras

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

Annotations already declare readOnly, idempotent, non-destructive behavior, so the description only needs to add context, and it does: it discloses the returned fields (nakshatra name, pada, deity, quality) and the cost tier. It does not say how the sidereal/school settings affect the result, which is the remaining behavioral gap; no contradiction with annotations.

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 front-loaded sentences describing action then output, plus a compact bracketed metadata block for group, endpoint, required inputs and cost. Nothing is redundant, though the required-parameters line duplicates what the schema's required array already declares.

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 the return-value sentence is a bonus rather than a necessity, and the annotations cover safety. But for a 13-parameter tool with 23% schema coverage, the description leaves too many computed defaults undocumented for an agent to call it confidently without opening the 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?

Schema description coverage is only 23% across 13 parameters, so the description carries a large burden and largely fails it. It never explains ayanamsa vs ayanamsaId, timezone vs timezoneOffset precedence, houseSystem, or cosmogram. Worse, 'using the sidereal zodiac' is silent on whether the caller must set zodiacType=sidereal, since the schema leaves that enum without a documented default.

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?

States a specific verb and resource ('Calculate the Nakshatra (lunar mansion) for each planet using the sidereal zodiac') and even names the returned fields. The phrase 'for each planet' implicitly separates it from astroway_vedic_panchang_nakshatra_of_day, but no sibling is named explicitly, so the differentiation is inferred rather than stated.

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?

Usage is only implied: the [Vedic] group tag and the required birth data signal that this is a natal-chart nakshatra computation, and no when-to-use, when-not-to-use, or alternative tool is given. An agent working from the 15+ Vedic siblings must infer the boundary itself.

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