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

Beyond the readOnlyHint and openWorldHint annotations, the description discloses return format (SVG plus base64), version and capacity limits, 400 behavior on overlength text, payment method and price, and that failed calls are not charged. This is substantial operational context.

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?

Front-loads the core action and compactly includes only operationally relevant details: format, limits, return value, error behavior, and price. There is no filler.

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?

With an output schema, full parameter description coverage, and safety annotations, the description supplies enough for correct invocation. Capacity limits, failure behavior, and payment terms are all present.

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%, so the baseline is 3, but the description adds exact byte capacities per error-correction level (17/14/11/7), which the schema only references generically. It does not describe scale, but the schema already fully covers that parameter.

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: makes a QR code as scalable SVG, pinned to 21x21 modules and version 1. It also gives exact capacity limits, so an agent knows precisely what this tool produces.

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?

Provides clear when-not constraints: larger versions are unsupported and longer text returns 400, with exact byte caps by EC level. It stops short of naming alternatives, though no direct QR-code sibling appears in the list.

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