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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, openWorldHint=false, so the safety profile is covered elsewhere. The description adds nothing beyond that — no indication of what data is returned, aggregation level, or currency/period handling — only a pointer to describe_operation.

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 first sentence is duplicated verbatim, which is pure waste, and the operation ID hash is not useful to a selecting agent. What little content exists is not organized to front-load purpose.

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 tool with nested objects, zero schema documentation, and no output schema, the description should carry the burden of explaining inputs and expected returns. It does neither, leaving the agent dependent on a separate describe_operation call before it can use this tool meaningfully.

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% with two opaque parameters (a free-form "query" object and an empty "params" object). The description offers no parameter meaning at all; the single pointer to describe_operation acknowledges the gap but does not compensate for it.

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 is the raw endpoint path repeated twice: "GET /api/billing/projected. GET /api/billing/projected." It never says in plain language what a projected billing figure is, what period it covers, or how it differs from siblings like get_subscription_billing_check or get_billing_available_months. This is essentially a restatement of the name/title.

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 statement of when to call this versus the many billing/subscription siblings. The only routing hint is that "describe_operation provides native request schemas," which tells the agent how to get schemas, not when this tool is the right one to invoke.

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