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

Annotations already declare destructive=true, idempotent=false and openWorld=true, and the description adds genuinely new behavioral facts: it spends wallet funds, submits an irreversible external transaction, and must not be retried blindly. It also requires confirming meter, amount, reference and recipient before invocation, which no annotation conveys.

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: trigger first, confirmation checklist in the middle, risk warning last. Every clause carries operational weight, and the irreversibility warning is placed where it will be read before invocation.

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 destructive, non-idempotent, money-spending mutation tool, the description covers trigger, prerequisites, confirmation requirements, and the retry hazard; the output schema handles return values. No material gap remains for correct invocation.

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%, so the baseline is 3; the description earns an increment by tying all four parameters into a pre-call confirmation checklist and by naming the meter's provenance. It does not add range or format detail beyond the schema, but the workflow semantics around the parameters are a real addition.

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 ('buy prepaid electricity') and immediately scopes it to a meter confirmed via check_electricity_meter, which cleanly separates it from siblings like create_airtime_order or create_data_order. An agent can select this tool without opening any schema.

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?

Explicit trigger condition ('when an authenticated SIMcloud user asks to buy prepaid electricity'), an explicit prerequisite (meter already confirmed with check_electricity_meter), and an explicit failure-mode instruction ('do not automatically retry an ambiguous result'). Nothing about when to use this versus alternatives 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.