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

Beyond the annotations (destructive, non-idempotent, open-world), the description discloses the cost (0.5 credits), the two-phase quote/confirmation flow, that nothing changes until the quote is confirmed, that the current page is loaded automatically, and that the card offers Undo. These are exactly the details an agent needs to call it safely, and nothing contradicts the annotation profile.

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 front-loaded with the primary action and the designId path, then the pasted-page fallback, then cost and the quote/confirmation flow. Every sentence carries actionable information with no repetition of schema or annotations.

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?

Given an output schema exists and the schema documents parameters at 86%, the description covers the critical behaviors an agent needs: the quote/confirmation gate, cost, undo, and the two input modes. It omits guidance on sectionId/selectedAreas scoping and referenceUrl, leaving a small gap for a 7-parameter mutation 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?

With 86% schema coverage the schema documents most parameters, and the description adds meaning the schema alone lacks: the mutual exclusivity of designId and currentHtml, and that a saved design's page is loaded rather than supplied. It doesn't explain sectionId, selectedAreas, or referenceUrl usage, so it stops short of fully enriching parameter semantics.

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 and resource ('make one focused change to a saved iter0 design') and immediately splits the two supported modes: editing a saved design by designId versus revising a pasted page by currentHtml. It names the related confirm/undo mechanics, so an agent can distinguish it from sibling tools like iter0_create_site or iter0_publish_site.

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 explicit conditionals: pass designId for a saved design, pass currentHtml when the page was pasted and no designId exists, and it explains that the first call only returns a price quote that must be confirmed (via the card, chat, or iter0_confirm_paid_action). It does not explicitly say when not to use this in favor of siblings such as iter0_design_layout or iter0_push_site, keeping it short of a 5.

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