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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds genuinely new behavioral facts: no AI call, nothing is created, the output includes a compliance checklist, launch checklist, 'honest limits' and a pre-filled GYSM builder link. It does not state the response shape or whether the builder link expires, which keeps it off a 5.

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 verb and resource, then layered detail, which is the right ordering. Every clause carries information (checklists, limits, link, Shopify caveat), though the single dense sentence with stacked parentheticals could be split for faster scanning.

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 four-parameter tool with no output schema, the description does the necessary work: it describes the artifact produced (checklists, limits, pre-filled builder link), discloses that nothing is created server-side, and bounds the deliverable. Missing only an explicit note on what the returned link/prompt looks like, which is minor given no output schema exists.

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%, so the schema already explains niche, currency, payments and products, and the description adds little on the parameters themselves. The one real addition is that Stripe Payment Links and thirdweb card-or-crypto checkout are 'set up in the seller's own accounts,' which gives context for the payments enum. Neither 'currency' nor 'products' is elaborated beyond the schema.

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 ('Plan a small online store') and enumerates the concrete deliverables (page sections, product features, checkout options, compliance and launch checklists, builder link), so the agent knows exactly what comes back. It also bounds scope with 'a single storefront page, not a full Shopify replacement.' It stops short of naming which sibling to use instead (e.g. plan_app or compare_ai_app_builders), so differentiation is by scope wording only.

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?

Useful context is implied: 'Free and instant: it makes no AI call and creates nothing' tells the agent this is a cheap planning step that precedes building, and the Shopify caveat sets expectations about when it is insufficient. However, there is no explicit when-to-use versus the sibling tools (plan_app, compare_ai_app_builders, get_build_link), so the routing decision 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.