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

Annotations are all false, providing essentially no signal, so the description carries the disclosure burden. It adds valuable behavioral traits: the 20-codes-per-month free quota, the Pro-tier requirement for PNG output, and the return payload (version, module grid, payload size). No contradiction with annotations; creating a QR code consuming quota is consistent with readOnlyHint=false.

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 tight sentences with zero filler: purpose and format options first, return values second, quota constraint last. Each sentence contributes distinct information and the most decision-relevant facts (what it does, what you get, what it costs) are front-loaded.

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 no output schema, the description's mention of return values (version, module grid, payload size) is genuinely useful. All 7 parameters are fully documented in the schema, and the description adds the quota and Pro-tier gating that the schema can't express. Minor gap: the one-hour download link expiry and overwrite semantics live only in parameter descriptions, which is acceptable given their 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 coverage is 100%, so the baseline is 3. The description mostly echoes what the schema already states (SVG default/free, PNG Pro, size relates to pixel dimensions for PNG). The cross-parameter note tying PNG to out_path and Pro adds a little meaning, but not enough to exceed the baseline given the schema's own rich parameter 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 opens with a specific verb+resource: 'turn text or a URL into a QR code,' which precisely states the tool's function. The 'text or URL' scope implicitly distinguishes it from specialized siblings like qr_vcard, qr_wifi, and qr_payment_sepa, signaling that this is the general-purpose QR generator.

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 implies when to use the tool (any text/URL QR need) and gives real decision context via the free/Pro format split and the '20 codes a month' quota. However, it never explicitly states when NOT to use it or names alternatives for specialized QR types (vCard, WiFi, SEPA), leaving the routing to inference.

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