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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so safety is covered. The description adds genuinely new operational context — the POST endpoint, the 20-credit Tier 2 cost, and the required inputs — which is real value, though it says nothing about latency, caching, or how the D12 result differs from the base chart. Cost disclosure is the main non-annotation contribution.

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?

It is compact and front-loaded: the chart identity and purpose come first, metadata after. The bracketed lines are formulaic but each carries distinct information (group, endpoint, required set, cost), so there is no filler — the issue is under-specification rather than verbosity.

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 return values need not be explained, but for a 15-parameter endpoint with only 33% schema coverage the description leaves the agent without guidance on the sidereal/zodiac configuration and compact-mode options that materially change results. For a highly specialized Vedic chart tool embedded in a dense sibling family, this is too thin.

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 carries a heavier burden than usual — yet it only restates the four required parameters already marked required in the schema. The eleven optional parameters (ayanamsa, ayanamsaId, timezone, timezoneOffset, zodiacType, houseSystem, fields, precision, cosmogram, city, name) get no elaboration, including the ones whose interaction rules (timezone vs timezoneOffset) are subtle.

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 the specific chart (Dwadasamsa / D12) and its astrological significations (parents, ancestral karma), which does differentiate it from the many sibling varga tools (d1, d9, d10, d16, etc.) that share the same shape. It stops short of stating the action verb ('compute/return the D12 divisional chart'), but the resource is 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?

There is no when-to-use guidance: nothing tells the agent when D12 is the right chart versus D9/D10/D60, nor what prerequisites (birth data quality, ayanamsa choice) apply. The bracketed metadata lists required fields and cost but not decision criteria, so the agent must infer selection from the significations alone.

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