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

Annotations already declare readOnly, idempotent, non-destructive, and open-world hints. The description adds non-obvious operational context: 'Priced $0.002 per call over x402 on Base; send a prepaid x-credit-token header for unlimited calls, or get 1 free call/day per tool' and 'No wallet or API key required.' This discloses cost, auth requirements, and rate limits beyond what annotations provide.

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?

The description is compact and front-loaded, leading with the core behavior in the first clause. There is slight redundancy between 'Text in, SVG (or data-URL) QR out' and the following sentence, but each subsequent sentence adds distinct value about use case, pricing, or auth.

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 two-parameter tool with an output schema and rich annotations, the description is fully sufficient. It covers required input, format defaults, target use case, offline behavior, pricing, free-tier availability, and auth requirements. An agent has all necessary information to select and invoke the tool correctly.

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 100%, giving a baseline of 3. The description adds meaningful clarification that the dataurl format produces a PNG ('format=dataurl PNG') and demonstrates the `text=` syntax. This goes beyond the schema's terse 'Payload' and 'svg (default) or dataurl' descriptions.

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 explicitly states the action: 'Encode text= into a QR code as SVG (default) or format=dataurl PNG.' This identifies the verb, resource, and output formats with specificity. No sibling tool performs QR encoding, so ambiguity with alternatives is minimal.

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 provides a clear intended context: 'Built for agents putting payment links, IBANs or URLs onto a page.' It also notes 'Offline, no upstream,' which informs when this tool is appropriate. However, it does not name explicit alternatives or exclusion conditions, so it stops short of a full 5.

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