Varga D9: Navamsa

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description's added value is operational: it discloses the endpoint, the mandatory inputs, and a concrete cost of 20 credits / Tier 2 — genuinely useful for planning and budget decisions. It adds nothing about what the response contains, but an output schema exists, so that omission is acceptable.

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?

One line of meaning followed by a compact bracketed metadata block; no wasted prose and the interpretive purpose is front-loaded before the endpoint/cost bookkeeping. The structured tags are scannable and each carries distinct information.

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 and annotations covering safety, the definition is adequate on the purpose and cost dimensions. But for a 13-parameter tool at 23% schema coverage it leaves the agent guessing about house system codes, ayanamsa selection, and timezone vs. timezoneOffset precedence — the kind of choice that can silently produce a wrong chart.

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 must compensate and does not: it merely repeats the four required fields the schema already marks required. Critical Vedics-specific choices are unexplained — notably houseSystem, whose 25 single-letter enum values (P, K, R, C...) have no description anywhere, and ayanamsaId/zodiacType which materially change a sidereal chart.

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?

Names the specific artifact (Navamsa / D9 divisional chart) and what it is read for (spouse, dharma), which distinguishes it from the many other varga siblings (D1, D7, D10, D60) whose names alone carry no interpretive meaning. It falls short of a 5 because it never says explicitly when D9 should be chosen over astroway_specialized_vedic_divisional or the D1 rasi chart.

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?

The parenthetical 'spouse, dharma; the most important divisional chart' implies the use case (relationship/marriage analysis) and signals priority among vargas, but there is no explicit when-to-use, no alternatives named, and no prerequisites beyond the required-parameter list. Usage must be inferred.

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