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

With no annotations, the description carries the full burden, and it delivers: it discloses auth requirements ('no API key needed'), output formats (SVG plus optional PNG data URL), and the critical behavioral trait that the QR is static and immutable once created. It even explains scan-counting consequences when comparing to the dynamic alternative.

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?

Three dense sentences, with the most important facts (free, no auth, output format) front-loaded and the alternative/use condition in a compact second half. No filler or repetition of schema fields.

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 low-complexity tool with 3 simple parameters and no output schema, the description plus schema fully cover what an agent needs: input, output, auth, and the key immutability constraint. The sibling-scoped alternative completes the decision context.

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 the baseline is 3; the schema already explains data, color, and format. The description reinforces the format behavior ('optionally also as a PNG data URL') and the data meaning but adds no significant detail beyond 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?

The description opens with a clear action: 'Render any URL or text as a QR code and return it as SVG,' naming both the resource and the output format. It also differentiates the tool by labeling this QR as STATIC with a baked-in destination, setting it apart from dynamic alternatives like shorten_url.

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?

It explicitly states when not to use this tool: if the destination might change, use shorten_url instead, with update_link called out for later edits. This gives an agent a concrete decision rule rather than leaving alternatives to inference.

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