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

With no annotations present, the description does real work: it declares the tool read-only (the safety profile an annotation would otherwise carry) and flags the important behavioral nuance that the QR image is not produced — the caller must render it from the url payload. It does not cover auth requirements or behavior on an invalid/unknown id, which keeps it below a 5.

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-loaded with purpose, then the returned fields, then the rendering caveat, then the read-only marker. Every clause adds information and there is no padding.

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 appropriately enumerates the return payload and warns that image rendering is the caller's job — enough to call it correctly for a one-parameter read tool. Minor gaps remain around error behavior for an unknown id.

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?

The single 'id' parameter has full schema description coverage ('Referral link id (UUID)'), so the schema carries the semantics. The description adds only the loose phrase 'for a link', confirming the id identifies a referral link but nothing beyond that. Baseline 3 applies.

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 resource — everything needed to render a share card/QR for a referral link — and enumerates the fields returned (url, short url, headline, description). It is clearly distinct in spirit from get_referral_overview and list_referred_users, though it never names a sibling to draw the boundary explicitly.

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?

Usage is only implied by the scenario ('to render the share card / QR'). There is no explicit statement of when to prefer this over get_referral_overview or create_referral_link, no preconditions, and no exclusions.

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