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

Annotations already declare readOnlyHint=true and openWorldHint=false; the description adds return behavior ("the image plus a shareable link") and the permanence trait of static codes (can't be edited after printing, no scan tracking). It resolves a real trap — the schema exposes a design.logo object, yet the description says logos are not allowed — but omits persistence lifetime of the shareable link and any rate/size limits.

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?

Four short sentences, all of them load-bearing: capability and auth first, then return value, then the static-vs-dynamic tradeoff with a sibling pointer, then the kind list and the logo restriction. No repetition of the title or boilerplate.

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?

The tool has deeply nested objects (design, content union) and no output schema, and the description covers enough to invoke it correctly: what to pass, which kinds exist, what comes back, and the logo caveat. It stops short of describing output format choice (png vs svg) and size defaults, which an agent would have to read from the schema.

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 only 25%, so the description must compensate, and it does for the highest-risk parameter: it enumerates the valid content kinds that map to the StaticQrContent oneOf, and it disables design.logo despite its presence in the schema. It says nothing about the format (png/svg), size, or the color/style/gradient options in QrDesign, which remain undocumented in prose.

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 ("Render a static QR code as an image") plus the scope constraint that no account or API key is needed. It also enumerates the seven encodable kinds (url, text, phone, sms, email, wifi, vcard), so an agent knows exactly what payloads are in play without opening the schema.

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?

Explicitly routes the agent away from this tool when editable or tracked codes are needed ("use create_qr_code with an API key for that") and states the preconditions under which this tool applies (free, no account). The "No logos" exclusion adds a second, concrete when-not condition.

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