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

Adds substantial context beyond annotations: pricing ($0.01/call via x402 USDC or card key, first 25 free, failed calls free), output format, and an explicit 'reads or computes only and changes nothing' that corroborates readOnlyHint. 'Each call is charged, so repeats are not free' also explains the idempotentHint=false annotation in billing terms.

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 purpose, then usage, then example, then pricing. Dense but every clause carries information; the pricing/billing sentence is long but justified since cost affects repeat-call decisions.

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?

No output schema exists, and the description compensates by naming both return artifacts (SVG and data URL). Combined with the input character cap, ECC options, and billing behavior, an agent has everything needed to call this 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%, so baseline is 3; the description adds a real constraint not in the schema — the 1,000-character UTF-8 limit — and restates the ECC option set with the M default. It does not add detail on size/margin beyond the schema, which is already well documented.

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 (generate) and resource (QR code), the accepted input (URL or any UTF-8 text up to 1,000 chars), the output form (scalable SVG plus ready-to-embed data URL), and supported ECC levels. No sibling tool does anything similar, so an agent can route this unambiguously.

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?

Gives concrete usage contexts ('put a link, Wi-Fi string or payment request on a page, label or ticket') and a literal example call with text=... No exclusions or alternatives are named, but no sibling overlaps this capability, so the gap is minor.

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