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

Annotations already indicate readOnlyHint and idempotentHint. The description adds useful behavioral details beyond those: invented ids are rejected rather than silently replaced, and no account is needed for basic queries. This gives the agent important expectations about validation and authentication.

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?

The description is compact, well-structured, and front-loaded with the core purpose. Every sentence adds distinct value: what it lists, why to call it early, and an additional no-account use case. No filler or repetition.

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 zero-parameter listing tool with an output schema and read-only/idempotent annotations, the description covers purpose, timing, error behavior, and access requirements. Nothing critical is missing for an agent to invoke and interpret this tool correctly.

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?

This tool has zero parameters and full schema coverage, so the baseline is 4. The description adds extra meaning by explaining that the returned design id is what goes into themeId, which helps the agent use the output correctly in downstream calls.

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 uses a specific verb ('Lists') and clear resource ('ready-made designs a form or funnel can use'), and connects the output to the themeId field. It clearly differentiates this from sibling tools like list_forms or list_templates by focusing on theme/design options.

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 explicitly instructs when to call it ('Call it before you set a design') and warns about invalid ids being rejected. It does not explicitly mention alternatives or when not to use it, but the guidance is clear and actionable for an agent.

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