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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false and destructiveHint=false, so the safety profile is covered. The description adds two genuinely useful bits of context the annotations cannot convey: the tradition grouping and the credit cost (10 credits, Tier 1). It still says nothing about output shape, time span covered, or reliance on lifespanYears.

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 brief and front-loads the one substantive phrase, so there is no bloat. But the bracket-tag metadata reads as packing rather than description, and the whole thing is under-specified for a technique this obscure.

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, and annotations cover safety. What is missing is the substance: what decennials are, what period the chart is broken into, and how lifespanYears affects the result — for a specialized Hellenistic technique among hundreds of siblings, that gap is material.

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% and the nested body schema is extremely detailed (date/time formats, timezone rules, house-system letters, rejected short forms). The description contributes nothing about parameters, so the schema does all the work; baseline 3 applies.

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 is essentially a restatement of the tool name and title: 'Hand's decennial timing technique' adds no verb, no output, and no scope beyond the label 'Decennials'. An agent unfamiliar with the technique learns nothing about what the call actually computes or returns. The tradition tag differentiates the school but not the capability.

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 guidance on when to use decennials versus the many neighboring time-lord siblings (profections, zodiacal releasing, firdaria, longevity hyleg, quarter lord). No prerequisites, no alternative routing, no exclusions are stated.

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