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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is fully covered without the description. The description does add non-annotation context — the endpoint and a concrete billing cost (20 credits, Tier 2) — which is genuinely useful for an agent weighing call cost, but says nothing about determinism, limits, or output shape beyond that.

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?

A single front-loaded sentence states the action and the technique, followed by a compact metadata block for group, endpoint, and cost. Nothing is padded, though the sentence is more definitional than operational.

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 full output schema, 100% parameter description coverage, and complete annotations, the description only needs to frame the operation, which it does. The gaps are minor — no note on the default period span or how sect is derived — and largely inferable from the schema's maxYears field.

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 carries the parameter semantics, including the nested birth-data requirements and the timezone/timezoneOffset interplay. The description adds nothing about maxYears, fields, or precision, so it sits at the baseline of 3 when structured data does the heavy lifting.

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 (Calculate) and a precise resource (Firdaria planetary periods), then adds the domain gloss 'traditional Persian time-lord system based on sect and planet order', which tells an agent what class of technique this is. It does not name or contrast any sibling prognostic tool, so an agent must rely on the technique name alone to distinguish it from profections, progressions, or returns.

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, no prerequisites, and no mention of the many sibling prognostic endpoints (profections, primary directions, solar return, etc.). The only implicit cue is the technique name itself, which leaves routing between prognostics tools entirely to inference.

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