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

With no annotations, the description carries the behavioral burden well by disclosing the return formats (scalable SVG and GIF data URL) and the per-call cost of 0.001 USDC via x402. It stops short of describing the first-call 402 payment flow, though the schema's paymentProof field covers that detail.

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 tightly written sentences with zero waste. The core encoding behavior is front-loaded, followed by output formats and cost.

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 tool with no annotations and no output schema, the description covers the essential behavior, outputs, and payment cost. The first-call payment mechanics are handled in the schema, so the remaining gap is minor.

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 75%, and the description adds meaningful semantic examples for the text parameter, including URLs, wallet addresses, and specific payment URI prefixes. The undocumented cellSize parameter and the basic ecc options are not clarified further, but the text semantics are a clear value-add.

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 states a specific verb and resource: encoding text, URLs, wallet addresses, or payment URIs into a QR code. It also specifies the output formats, making the tool's function unambiguous even without sibling differentiation.

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 implies when to use the tool by listing supported content types, such as wallet addresses and ethereum:/solana: payment URIs. However, it does not explicitly say when to use this versus alternatives or mention any exclusions or prerequisites beyond the payment note.

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