render_davison_chart

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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the safety profile is covered. The description adds genuinely non-redundant behavior: the output is a 720px PNG wheel displayed directly to the user — key information for a render tool. It does not say what happens if person_a or person_b is omitted, which matters since all parameters are optional.

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?

Two tight sentences with zero waste; the artifact and its dimensions are front-loaded, and the input-contract note follows. Nothing could be removed without losing information.

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 no output schema, the description correctly states the return form (720px PNG shown to the user), which is the main thing an agent needs. Remaining gaps — prerequisite ordering relative to calculate_davison_chart and the undocumented house_system — are modest for a straightforward render tool with annotations covering safety.

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%, so the description carries the burden, yet it only delegates via "same inputs as calculate_davison_chart" and "two people" — a useful pointer but not a substitute for explaining person_a/person_b. The house_system parameter (default placidus) is never mentioned, nor is the consequence of the null-defaulted birth fields, so nearly all parameter meaning remains unstated.

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 (render) plus the exact resource (Davison relationship / time-space midpoint chart of two people) and the concrete artifact produced (720px PNG wheel). It also names the sibling calculate_davison_chart, so an agent can immediately tell the drawing tool from the computational one in the crowded chart family.

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?

"Same inputs as calculate_davison_chart" establishes context and implicitly contrasts this rendering tool with its calculation sibling, making the use case (produce a visual for the user) clear. It stops short of stating when not to use it or whether calculate_davison_chart should be called first, so it is clear context without explicit exclusions.

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