Decennials

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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful operational context the annotations lack: the POST endpoint and a 10-credit Tier 1 cost, which matters for an agent budgeting calls. It does not disclose anything about the calculation's basis (e.g. how lifespanYears shapes the periods), so it is additive but thin.

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?

One sentence up front, then bracketed metadata lines: zero padding and the core identification is front-loaded. The size is appropriate for the information present; the issue is what is missing, not what is wasted.

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 and 100% schema coverage, the description needn't explain inputs or return values, and annotations cover safety. What remains missing is the one thing structured fields can't supply: a plain statement of what a decennial chart yields and when to prefer it over the neighbouring Hellenistic techniques.

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 birth-data object documents date/time/latitude/longitude, timezone, ayanamsa and houseSystem in detail, so the schema carries the burden. The description adds nothing about the one parameter unique to this tool, lifespanYears (default 90, range 20–120), which visibly shapes a decennial calculation — a missed opportunity rather than a gap, so baseline 3.

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?

It names a specific technique ("Hand's decennial timing technique"), which is a recognizable resource in the Hellenistic Hand family and is reinforced by the group tag. But it never says what the technique actually produces — a time-lord sequence of ten-year periods? — so an agent that doesn't already know Hand's decennials cannot tell what it gets back. The sibling list is full of other Hellenistic time-lord tools (quarter_lord, lots_of_seven, perfections), and nothing here distinguishes this one from them.

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 statement of when to reach for decennials versus the other Hellenistic timing methods in the sibling set. No prerequisites, no exclusions, no alternative named. The group tag implies a family but gives no routing logic.

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