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

Annotations cover the safety profile (readOnlyHint=false, destructiveHint=false, idempotentHint=false), and the description adds real behavioral context: the output is a 'temporary ... download page', it 'Never starts checkout', and it does not save or overwrite a project. These are meaningful non-schema traits, though return/lifetime details are left to the output schema.

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 clauses, front-loaded with the core action, then the entitlement fallback and two negative scoping constraints. Every sentence earns its place with no redundancy.

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?

For a 2-parameter tool with a full output schema and complete schema descriptions, the description supplies the missing behavioral context (temporary page, entitlement gate, no checkout, no persistence) without needing to explain return values.

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 both parameters (format, settings) are already fully documented, including enum, defaults, and nested properties. The description only restates the format options (STL or 3MF) and that the design must be 'complete', adding no syntax or constraint beyond the schema, so the 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?

States a specific verb and resource: 'Prepare a temporary STL or 3MF download page for the provided complete design.' It also distinguishes itself from siblings by negating persistence ('Does not save or overwrite a project') and checkout behavior, so an agent can separate it from save_design and any purchase tool.

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 clear context and a fallback: it uses the account's 'existing export entitlement' and says to 'return a neutral explanation and stop' if unavailable. It does not explicitly name check_export_access as the prerequisite sibling, so the when-to-use routing is implied rather than spelled out.

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