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

Annotations already declare read-only, idempotent, non-destructive, closed-world behaviour, so the safety profile is covered. The description adds genuinely useful non-schema context — the 20-credit Tier 2 cost and the concrete period-length formula — but says nothing about response size, ordering, or breakdown behaviour.

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?

Three compact fragments: identity, default, formula, followed by group and cost tags. Front-loaded and free of filler, though the formula sentence is terse enough to require domain knowledge to parse.

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 a 100%-covered schema and an output schema present, the description need not explain return values. It covers the default date, the computation model, and cost, leaving only the level-vs-sibling routing implicit, which is a minor gap.

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 birth-data object, targetDate/targetTime/targetTzOffset, fields and precision are all documented downstream. The description reinforces only targetDate's today-UTC default; baseline 3 applies when the schema carries the parameter burden.

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/resource: it returns the 8 Yogini antardasha sub-periods of the running mahadasha at targetDate, and the formula clarifies what an antardasha is. It is distinguishable from the yogini_maha sibling by the 'sub-periods of the running MD' framing, but it never names the neighbouring levels (maha/pratyantar/prana/sookshma) to make the routing explicit.

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?

Only practical guidance is that targetDate defaults to today UTC. There is no statement of when to pick this depth over yogini_maha or yogini_pratyantar, and no prerequisites or exclusions are given, so the agent must infer the level hierarchy from the tool name alone.

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