Usage

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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is fully covered structurally. The description adds only that the data is real-time and scoped to the caller's account (implying authentication). It says nothing about rate limits, caching/freshness semantics, or what happens on an unauthenticated call.

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 substantive sentence is efficient and front-loads the two returned resources. The leading 'Usage.' merely restates the name and title and adds no information, a small but avoidable waste.

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 zero-parameter read tool the description covers what it returns at a high level, but there is no output schema, so the shape of the usage statistics and credit balance (units, counters, reset periods) is left entirely undefined. A single clause on the returned fields would close the remaining gap for an agent trying to consume the result.

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?

The tool takes zero parameters, so there is no parameter meaning for the description to supply; the baseline for a no-parameter tool applies. Nothing in the description contradicts or misdescribes the empty input schema.

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 gives a specific verb (Retrieve) and two named resources (real-time usage statistics and credit balance) scoped to 'your Veille account', so an agent knows exactly what this returns. It does not differentiate from the sibling 'stats' tool, which is a plausible source of confusion between usage statistics and a general stats endpoint.

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?

There is no explicit when-to-use or when-not-to-use guidance and no named alternative. The word 'real-time' weakly implies this is for live balance checks rather than historical reporting, but the agent must infer that on its own, and the 'stats' sibling is never mentioned.

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