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

Annotations already declare readOnlyHint, destructiveHint=false, and openWorldHint=false, so the safety profile is handled. The description adds genuine behavioral context beyond that: it returns each field's name and data type, and an empty object signals the design cannot be autofilled. That return-shape disclosure is valuable and not in the 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?

Front-loaded with the core behavior, then usage, then exclusion, then requirements and return shape. Every sentence carries information, though the three near-synonymous use-case phrases are slightly redundant.

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?

Despite having no output schema, the description fully specifies the return value (field names and types) and the critical edge case (empty object = not autofillable), which is the main thing an agent needs to interpret the result. Nothing essential is missing for a 2-param read tool.

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 (including user_intent) are already documented in the schema. The description only restates 'Requires a design_id' without adding format or constraint detail beyond what the schema provides, so the baseline of 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 verb (verify/list) and resource (fillable data fields of a selected existing Canva design), and explicitly distinguishes itself from the sibling get-brand-template-dataset with 'Not for a reusable Brand Template.' An agent can tell exactly what this returns.

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?

It gives three concrete use cases ('see whether a specific past design can be populated,' 'understand if an existing design can be autofilled,' 'see the fields available') plus an explicit exclusion for Brand Templates. Both when-to-use and when-not-to-use are covered.

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