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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new context: the call is 'Free' (no credit cost) and usage-history scoping is unavailable here. It stops short of describing return shape or pagination, but with annotations doing heavy lifting that is a minor gap.

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?

Front-loads the usage trigger, then adds the pre-cost-check use case and the exclusion. Two sentences, no filler, every clause earns its place.

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?

There is no output schema, so the description usefully names the fields returned (plan, credit balance, allowance, refill date, trial). It does not detail response structure, but for a zero-argument read tool this is nearly complete.

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?

Zero parameters, so the schema carries no semantics to compensate for; baseline is 4. The description properly focuses on behavior and triggers rather than inventing parameter detail.

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 ('Get') and resource ('account and credits') and enumerates the concrete fields surfaced (plan, credit balance, monthly allowance, next refill date, trial), which lets an agent distinguish it from siblings like xcut_get_breakouts or xcut_get_content.

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 triggers ('when the user asks about their XcutAI plan, credit balance...'), a proactive trigger ('before starting an import or analysis that costs credits'), and an explicit exclusion ('Do not use for usage history'). This is a textbook when/when-not specification.

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