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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description usefully adds that rendering is 'pure server-side, no browser needed' and the 10-credit Tier 1 cost, but omits that supplying a pre-computed chart instead of birth data drops the cost to 1 credit (only in the schema).

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 the rendering purpose front-loaded, followed by a compact bracketed metadata block. Nothing is padded or duplicated, though the metadata block is slightly less critical than the core sentence it follows.

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 values need not be explained, and annotations carry the safety profile. The description covers purpose, delivery mechanism and cost; the two-mode input (birth data vs pre-computed chart) is left to the schema, which handles it well.

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 67% and the schema is very rich (validation rules, timezone/ayanamsa semantics, house system notes, labels/theme docs). The description adds no parameter-level meaning at all, so it neither compensates for the coverage gap nor earns credit over the schema.

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 (Western natal wheel) and enumerates the rendered content (signs ring, houses ring, planets, aspect lines). The 'Western natal' qualifier implicitly separates it from the Vedic wheels and from bi/tri-wheel and composite siblings, but it never names an alternative 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?

There is no when-to-use or when-not-to-use guidance and no mention of sibling renderers (vedic wheels, bi-wheel, aspect grid). The only contextual lines are metadata (group, endpoint, credit cost), which do not help an agent choose between tools.

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