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

Annotations already establish readOnly, idempotent, non-destructive, closed-world behavior, so the bar is lower; the description usefully adds the POST endpoint and the 10-credit (Tier 1) cost, which is real decision-relevant context. It does not disclose the output-format default, which is 'json' in the schema despite the title saying '(SVG)' — a mismatch an agent would otherwise miss.

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 substantive sentence followed by compact bracketed metadata; the plot definition is front-loaded and nothing is padded. The group/endpoint/required/cost tags earn their place as scannable facts.

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-value explanation is not required, but the definition says nothing about the format default, the date-range constraints, or how the biorhythm origin (birth) relates to rangeStart/rangeEnd for a tool with 6 parameters including a nested options object. Adequate to identify the tool, thin for invoking it correctly.

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 only 33%: size, width, height, format, showAspects, showRetrograde and the three date parameters carry no schema text, and the description compensates only by repeating which three are required. No meaning is added about date semantics (is rangeStart inclusive?), valid range span, or how the options interact with the JSON/SVG choice.

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 concrete output ('Three-curve sine plot') and the exact subject matter with the physical/emotional/intellectual cycle lengths (23/28/33 days) since birth, which is specific enough to separate it from the other astroway_render_* siblings (wheel, timeline, cosmogram). It stops short of an explicit verb or a named alternative, so it is clear but not maximally distinct.

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 choose this over astroway_render_timeline or the other rendering tools, and no advice on when to prefer SVG versus JSON output. The only routing signal is the 'Required' list, which restates the schema rather than telling the agent when this tool is the right call.

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