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

Annotations already mark the tool as destructive and not read-only. The description adds valuable context: it cancels all eligible eSIMs in the same order and requires a confirm step. This goes beyond the structured annotations without contradicting them.

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 short sentences, each carrying distinct information: what is cancelled, eligibility/refund, bulk behavior, and the confirmation step. No filler or redundancy.

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?

Adequately covers the core behaviors: eligibility, refund, bulk scope, and two-step confirmation. Given there is no output schema, slightly more detail about post-cancellation effects or order could improve completeness, but it is largely sufficient.

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 100% and already describes iccid and confirm (including preview vs. execute). The description restates the confirm behavior but adds no new parameter-level detail 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 clearly states the tool cancels eSIMs that have never been installed/activated and refunds to balance. It includes the bulk behavior ('Cancels EVERY eligible eSIM') and a two-step execution, making it easily distinguishable from siblings like suspend_esim or activate_esim.

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 a clear eligibility condition: use for eSIMs never installed or activated. It does not explicitly name alternatives or exclusions (e.g., 'for active eSIMs use suspend_esim'), but the condition is specific enough to guide selection.

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