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

Annotations already declare this is a read-only, idempotent, non-destructive, closed-world call, so the safety burden is largely covered. The description adds non-obvious behavior beyond that: the default of 'today UTC' for targetDate and the cost (20 credits, Tier 2), which help an agent plan calls. It does not discuss response size or limits, but with an output schema present that 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?

The core sentence is front-loaded and dense with meaning; the formula earns its place by disambiguating what a 'sub-period' means here. The bracketed group/endpoint/cost lines add noise but carry operationally useful tier pricing.

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 annotations covering safety, a rich input schema describing all nested birth-data fields, and an output schema handling the return shape, the description only needs to establish scope and defaults — which it does, plus cost tier. Minor gap: no indication of the level relative to sibling dasha depths.

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 100%, so the schema documents the parameters in detail; baseline is 3. The description only adds the targetDate default (today UTC), which is genuinely extra information, but the P.years/Q.years references in the formula are dasha concepts, not parameters.

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 the specific resource (Yogini Antardasha) and scope (8 sub-periods of the running MD at targetDate), and even gives the computation formula, so an agent knows this returns the second dasha level. It does not explicitly contrast itself with the sibling levels yogini_pratyantar/prana/sookshma, leaving the hierarchy depth to be inferred from the names.

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 formula and 'sub-periods of the running MD' imply when the tool applies, and the default targetDate is stated, but there is no explicit guidance on when to pick this depth versus the maha/pratyantar/prana siblings, and no stated prerequisites.

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