Composite Chart (SVG)

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), and the description adds genuinely decision-relevant context: the POST endpoint, the 10-credit Tier 1 cost, and the two-stage compute-then-render behaviour. It stops short of noting that the response format is controlled by options.format (schema defaults to json), which matters for a tool titled SVG.

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 sentences front-load what the tool does, followed by three short metadata lines (group, endpoint, cost) that each carry operational value. No filler or restatement of the title.

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 the annotations plus schema are rich. What is missing is disambiguation from astroway_relational_composite and the default json-vs-SVG output behaviour, both of which an agent needs before committing 10 credits.

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% and the body/chart objects are documented in depth. The description adds nothing about the parameters, not even that a single wrapped body containing chart1, chart2 and options is required. Baseline 3 is appropriate when 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 chain and resource: computes a midpoint composite from two natal inputs, then renders it as a Western wheel. That distinguishes it from astroway_render_wheel_western (single chart) and implies a split from astroway_relational_composite, though it never names the sibling it is not.

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 phrase 'from two natal inputs' implies the precondition, but there is no explicit when-to-use or when-not, and no routing guidance among the dense render_* / relational_* family. An agent must infer that this is the image-producing path rather than the data-producing one.

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