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

Annotations already declare readOnly, idempotent, closed-world. The description adds the cost tier (10 credits) and the fact it produces an SVG image, plus layout semantics. It doesn't mention the default output format (json per schema) or size/theme defaults, so there is some uncovered behavioral surface.

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 plus grouped metadata lines. The layout constraint is front-loaded and nothing is wasted; slightly terse rather than bloated.

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?

For a rendering tool with a full input schema, output schema, and read-only annotations, the essential call mechanics are covered elsewhere. However, the description omits key decision context: which chart the wheel is drawn for (natal data flows from body), how it differs from the East/North variants, and the default format being json rather than SVG despite the title.

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%, so the schema already documents body, fields and precision in detail. The description adds nothing parameter-specific, which is the correct baseline given the schema does the heavy lifting.

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) and resource (Vedic wheel, South Indian 4×4 grid), and describes the layout detail (Pisces top-left, signs fixed, house numbers where lagna falls). This clearly distinguishes it from the two sibling variants astroway_render_wheel_vedic_east and astroway_render_wheel_vedic_north, though it never names them explicitly.

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?

No statement of when to use this South Indian layout versus the East/North Indian siblings or the Western wheel. The layout convention is described but no routing guidance is given, leaving an agent to infer the choice from the name alone.

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