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

Annotations only cover the read-only/idempotent safety profile; the description adds substantial behavioral detail beyond them: the exact return contents (rising sign plus every planet's sign and house), the extra D9-only ishta/palana deities from the karakamsha and the D10 per-planet deity, and the precision sensitivity of the rising sign (~13 and ~12 minutes of birth time).

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?

Four sentences, front-loaded with the usage trigger and no filler. The parenthetical example phrases make it dense but each sentence carries new information (triggers, chart param, return shape, birth-data precision).

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 must carry the return contract — and it does, spelling out the rising sign, planetary placements per chart, and the chart-specific deity fields. Combined with the birth-time precision warning, an agent has everything needed to call and interpret the tool.

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 100%, so the baseline is 3, but the description adds astrological meaning the schema lacks: it explains that 'chart' selects d9 vs. d10 for marriage vs. career, and that birth_time accuracy matters because the D9 rising sign shifts roughly every 13 minutes. Format syntax itself is left 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 names a specific resource (navamsa/D9 and dashamsha/D10 divisional charts) and its interpretive purpose (marriage and inner strength vs. career), which separates it from the generic vedic_birth_chart sibling. Example user phrasings make the target unambiguous.

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?

It gives explicit trigger conditions — 'Use this when someone asks for their navamsa (D9) chart... or their dashamsha (D10) chart' — plus concrete utterance examples. It does not, however, state when NOT to use it or name the sibling (vedic_birth_chart, vedic_rising_sign) that handles the base rasi chart.

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