render_visual_card

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

With no annotations, the description carries the burden and does disclose key traits: determinism, typo-free output, the return shape (SVG + data URI), and a concrete cost of $0.025 USDC on Base. It stops short of explaining how payment is authorized, whether calls are idempotent, or what happens on payment failure.

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?

One dense sentence with the artifact list front-loaded and the price/output format trailing. Every clause carries information; nothing is padding.

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 an 11-parameter, no-annotation, no-output-schema tool, the description establishes what is produced and at what cost, but leaves the caller unable to determine which optional fields are meaningful for which template or how payment is settled. Adequate to identify the tool, insufficient to invoke it confidently.

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 coverage is only 27% across 11 parameters, so the description must compensate. It partially does by naming the three templates and implying sparkline/metric inputs, but says nothing about theme, badge, brandName, subtitle, or accentColor, and never explains that template selection governs which other fields matter (additionalProperties is false).

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?

A specific verb (Render) applied to three named, dimensioned artifacts (1200x630 OpenGraph banner, 1080x1350 social KPI slide, trading signal sparkline card) plus the exact output format (SVG + data URI). No sibling tool produces images, so the differentiation is implicit but unmistakable.

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 template names imply which use case each output serves, but there is no explicit when-to-use/when-not-to-use guidance and no statement of prerequisites for the paid call. An agent can infer intent from the artifact descriptions but must guess about payment flow and preconditions.

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