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

Beyond the annotations (idempotent, non-destructive), the description discloses two critical behaviors: 'Costs 1 credit per call' and 'Returns a temporary download link (valid 15 minutes).' It also tells the agent to include the link in the reply. These add significant behavioral context not present in annotations.

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 sentences with no redundancy. The first sentence states the core purpose and the format options, the second covers cost, the third the link validity, and the fourth the required action for the agent. Each sentence earns its place, and the purpose is 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?

The description is complete for an agent to call this tool correctly. It covers the input (text/link with max length), the behavior (cost, temporary link), and the required follow-up action (include link in reply). No output schema exists, and the parameters are fully documented in the schema. Nothing an agent needs is missing.

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 schema covers 100% of parameters with descriptions, so the baseline is 3. The description reinforces the max length (1500) and mentions the output format (PNG/SVG), but does not add new parameter-level semantics beyond what the schema already provides. It does not compensate for any schema gaps because there are none.

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 verb and resource: 'Turns a link or any text (max 1500 characters) into a QR code.' It also mentions the output formats (PNG or SVG) and the maximum length. This clearly distinguishes it from the sibling tools, none of which generate QR codes.

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 tells the agent what the tool does (converts text/link to QR code) and provides an explicit post-call instruction: 'Always include that link in your reply so the user can open or download the file.' It does not mention alternatives, but no alternatives exist among siblings, so the usage context is clear.

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