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

With no annotations, the description carries the behavioral burden and does a solid job: it discloses that output is watermarked, that both URLs and inline image content are returned (one per zone), and the async queue behavior with the exact pending shape and retryAfterSec. Missing only auth/permission requirements and any caching or rate-limit notes.

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?

Three dense sentences, front-loaded with the core verb and resource, and the retry instruction is placed last where it belongs. Slight duplication of the zoneId rule already in the schema keeps it from a perfect score.

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 correctly compensates by describing the return shape (URLs plus inline images, one per zone) and the pending-status case. It is nearly complete, lacking only error behavior for invalid or non-VALID designs and any auth context.

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 description coverage is 100%, and the schema already documents both designId (dsg_… id) and zoneId (render a single zone; omit for all). The description's zone guidance restates the schema rather than adding new meaning like ID format or multi-zone batching semantics, 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 (render) and resource (watermarked PNG preview) scoped to a design, and clarifies it covers all zones or one. It is unmistakably distinct from siblings like create_design, get_design, and update_design.

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?

Explains the when: render a VALID design, and the condition selecting zoneId (render one zone vs. omit for all). It does not name alternatives or explicitly state prerequisites such as when a design becomes VALID, but 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.