preview_qrcode

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds genuinely useful behavioral context that annotations cannot: the return payload is an image rendered for inspection, which matters because there is no output schema. It stops short of noting any cost, rate limit, or caching behavior.

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 zero filler; the core action and the return behavior come first, and the disambiguation with the sibling is placed last where it belongs.

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 simple read-only generator with a fully documented 4-parameter schema, the description covers purpose, output shape, and the alternative. With no output schema present, a bit more on the image format or dimensions returned would close the remaining gap.

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 url, enabled, url_type, and dimension are already fully documented in the schema, including defaults and enum-like values. The description adds no formatting or sizing nuance beyond that, so the baseline 3 applies.

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 and resource ("Generate a QR-code PNG for an invitation") and explicitly distinguishes itself from the sibling that commits the artifact ("Use set_card_project_qrcode to actually place it on a card"). An agent can separate this preview tool from the setter without opening either schema.

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?

Names the alternative tool and the condition that selects it: use this to inspect, use set_card_project_qrcode to persist. That is a clear routing rule, though it doesn't spell out when a preview is unnecessary or whether it has side effects on the card project.

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