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

Annotations already cover the safety profile (read-only, idempotent, non-destructive, closed-world), so the description wisely spends its budget on behavior the annotations cannot convey: credit cost per call (3, charged only on success), a free sandbox key returning a sample, and deterministic output. These are exactly the operational traits an agent needs before committing to a call.

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?

Front-loaded with the usage trigger before mechanics, and the cost/determinism lines are short and earn their place. The inline example-arguments JSON is slightly heavy but directly aids invocation, so the cost is minor.

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, the description need not explain return values, and it fills the remaining gaps: trigger condition, billing model, determinism guarantee, and a worked argument example. Nothing an agent needs to invoke it correctly is missing.

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 already documents birthData, its nested fields, timezone format and referenceDate defaults. The description only restates the referenceDate default (already in the schema) and adds an example argument set, so baseline 3 is appropriate.

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 and resource ('Plain-language guidance cards for each running daśā level') and draws a useful contrast ('Guidance, not prediction'). This conceptually separates it from raw-data tools like get_dasha, but it never names or explicitly distinguishes itself from its actual siblings, so the differentiation is implied rather than stated.

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 opening sentence gives clear usage context: use it when the user asks how to conduct themselves in their current period, with the reason that distinguishes it from pure prediction. It provides no explicit exclusions or named alternatives, so an agent must infer when to pick get_dasha or get_forecast instead.

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