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

Annotations cover the safety profile (destructiveHint=true, idempotentHint=true), and the description corroborates and enriches it: re-using an uploadId replaces the stored design (the destructive behavior, spelled out), the HTML is temporarily hosted at TheySaid (external data egress), and the return shape/next step is named. No contradictions with the hints.

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 fallback condition, then inputs, then return/next step. Dense but every sentence carries information (failure mode, temporary hosting, replacement semantics, non-actions). Slightly long, but no filler.

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 an output schema existing, the description still names the returned fields and the required next call. Combined with the failure-mode trigger, replacement caveat, and explicit non-start of a test, an agent has everything needed to invoke this correctly and know what comes next.

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 0%, so the description carries the burden. It clarifies that `html` must be the complete, self-contained design HTML and that `uploadId` determines where the design is hosted and that reuse replaces prior content. It does not specify the uploadId's format or origin beyond pointing at prepare_design_snapshot, which is the only real gap.

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 (upload a design snapshot) and immediately frames it as the fallback path when the PUT to the `uploadUrl` from prepare_design_snapshot is blocked. This distinguishes it cleanly from sibling prepare_design_snapshot and from check_design_snapshot, which is named as the successor step.

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?

Explicit when-to-use ('fallback ... for when the PUT ... is blocked by the environment's network'), a concrete failure example ('Host not in allowlist'), the prerequisite tool that produces the inputs, the follow-up tool, and a negative exclusion ('This tool does not start a test'). Nothing is left to inference.

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