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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the agent knows this mutates state; the description adds value beyond that by disclosing the refund effect on the wallet and the uc_live_ API key requirement. It still does not state whether the cancellation is reversible or what happens to an already-received SMS/code.

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?

Two short sentences, front-loaded with the action and trigger, with no filler. Every clause carries information the agent needs.

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?

Covers the trigger, the credit-refund outcome, and the auth requirement, which is reasonable for a mutation tool without an output schema. It is nonetheless incomplete on the parameters and on how to pick this tool over ucode_sms_cancel_rental.

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 0% and none of the three parameters (id, reason, reasonNote) are explained in the description. The phrase "when no SMS arrived" loosely hints at the code_not_arrived enum value but never names it or clarifies what id refers to (rental id?), so the description fails to compensate for the coverage gap.

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 ("Cancel an agent rental") and adds the financial effect ("credits return to the agent wallet"), which is more than a restatement of the name. However, it does not distinguish itself from the near-identical sibling ucode_sms_cancel_rental, leaving the agent to guess which cancel tool applies.

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?

Provides a triggering condition ("when no SMS arrived"), which implies usage context, but gives no explicit exclusions or alternatives despite ucode_sms_cancel_rental existing as a plausible competing choice. The condition is also narrower than the schema's reason enum, which allows service_rejected, number_has_account, and other.

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