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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds the credit cost and tier, which is genuine value beyond annotations, but it omits the behavioral distinction that passing a pre-computed chart costs 1 credit instead of 10.

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, front-loaded with the output shape, plus a compact cost tag. Nothing is wasted, though the [Group: Visualization] tag is largely redundant with the name prefix.

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 described, and annotations cover safety. However, for a tool whose schema offers two very different input paths with different costs, the description says nothing about either, leaving the agent to discover the cheaper chart-replay route only by reading the 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 67% and the schema itself is extremely detailed (birth-data vs chart union, labels, theme, format, precision). The description adds no parameter meaning at all, so it sits at the baseline for a partially documented 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 rendered artifact: a triangular aspect matrix where rows/columns are planets and each cell carries an aspect glyph plus orb, with a 'standard textbook layout' note. This is clear enough to separate it from siblings like astroway_aspects_aspect_bar or astroway_render_wheel_western, though it never explicitly says it produces an SVG (that is left to the title).

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 description gives no when-to-use guidance and names no alternative among the many sibling render/aspect tools. The only contextual signal is the cost tag (10 credits), which helps an agent budget but not choose.

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