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

Beyond the annotations, the description discloses a meaningful behavioral trait: the tool waits up to about 25 seconds for payment and eSIM readiness. It also states what is returned and explicitly notes that installation codes are never returned, though it does not discuss authentication or rate limits.

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 a single dense sentence, but it is front-loaded with the trigger context and then explains the outcome. The parenthetical examples and return details are useful, though the sentence is somewhat packed.

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 the simple two-parameter schema, existing output schema, and read-only annotations, the description is complete enough for correct invocation. It covers trigger timing, wait behavior, return content, and the key exclusion about installation codes.

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 input schema already documents checkout_id and locale fully. The description only indirectly links checkout_id to start_checkout and adds no additional parameter semantics beyond what the schema provides.

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 resource and outcome: it shows whether payment arrived and whether the eSIM is ready after payment through start_checkout. It also names concrete return content (eSIM, install/manage link, Simvito app) and a key limitation, making it distinguishable from siblings like start_checkout.

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?

The description gives clear usage context: after the user pays through start_checkout's links, especially when they say 'paid' or ask 'is my eSIM ready?'. It does not explicitly say when not to use this tool or name alternatives such as list_my_esims, so it falls short of full when/when-not guidance.

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