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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered; the description adds domain-specific value with 'No order is placed and no payment is made by this tool,' directly countering the transactional implication of the tool name. Auth requirements and link expiry are still undisclosed.

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 tight sentences with no waste: purpose first, then the non-transactional clarification, then the parameter behavior. Every sentence earns its place and the most important constraint (no purchase) is front-loaded after the purpose.

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 does state what comes back (a URL) and how the two parameter modes shape it, and annotations cover safety. Minor gaps remain around link lifetime and the source of valid sku/destination values.

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 coverage is only 33% (only locale is documented), so the description must carry sku and destination — and it does, explaining that sku selects the plan and destination alone produces an unpreselected page. It does not say where sku/destination values come from or their format, so it is not fully compensating.

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: 'Return the URL of a plan's page on simsima.io, with the plan preselected.' It also preempts the misleading 'checkout' name by clarifying it is a link generator, not a purchase. It does not name or contrast any sibling tool, so it stops short of a 5.

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?

Clearly delineates the two invocation modes: pass a sku to preselect a plan, or pass only a destination to land on a destination page with no plan. That is actionable context, but it never states when to choose this tool over siblings like get_plan or recommend_plan.

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