Biorhythm (JSON)

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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the bar is lower. The description adds genuinely useful context beyond that: the three cycle periods and their lengths, the meaning of the 'critical days' field, and the 10-credit Tier 1 cost. It does not say what date range is used by default when rangeStart/rangeEnd are omitted, which is the main remaining behavioral unknown.

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?

The two prose sentences are tight and front-loaded with the most important information (what is returned, then the sibling relationship). The bracketed metadata lines are boilerplate but compact and each carries a distinct fact (group, endpoint, required param, credit cost). Minor redundancy: 'Required: birthDate' repeats the schema.

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 the description needn't explain return shape, and the annotation set covers the safety profile. What remains missing is any account of the date-range parameters and default windowing for a tool whose entire purpose is a per-day series — a meaningful gap for a 3-parameter, 0%-coverage schema.

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 0% for three parameters, so the description bears full responsibility. It only restates the required birthDate (already in the schema's required list) and says nothing about rangeStart/rangeEnd — their defaults, whether the range is inclusive, or the maximum span. An agent cannot determine what a call without a range returns.

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 names the exact output: physical (23d), emotional (28d) and intellectual (33d) cycle values per day plus zero-crossing critical days. It also implicitly positions itself against the sibling astroway_render_biorhythm by calling itself the 'data twin of POST /render/biorhythm'. It lacks an explicit verb ('compute/return'), but the resource and scope are unmistakable.

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 'data twin of POST /render/biorhythm' phrasing hints that this is the JSON alternative to the render/image sibling, which is useful implied guidance. However, there is no explicit statement of when to prefer this over astroway_render_biorhythm, astroway_wellness_cycle, or astroway_wellness_sleep_cycles, and no exclusions or preconditions beyond the required birthDate.

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