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

The description discloses authentication behavior ('Pass email + password ... for Basic auth, or omit both to use the configured API key') and the polling context, which adds value beyond the readOnlyHint/idempotentHint annotations. It does not contradict the annotations and explains what the tool checks without claiming side effects.

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 description is front-loaded with the single-sentence purpose, followed by a compact usage scenario, args, and returns. Every sentence contributes: use case, auth mode, and expected output.

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 read-only poll tool with two optional params and an output schema, the description covers purpose, when to call it, auth alternatives, and return fields. There is no missing operational detail an agent needs to invoke it safely and correctly.

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 adds useful coupling by saying the credentials come from create_account and that omitting both uses the API key. This gives the agent more operational guidance than the schema's standalone field descriptions.

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 opening sentence names a specific verb and resource—'Check account verification status, credit balance, and API key count'—and the Returns line reinforces what is queried. This clearly differentiates it from siblings like get_balance by covering verification and API key count in addition to balance.

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?

It explicitly instructs when to use the tool: 'Use this after create_account to poll whether the user has clicked the verification link.' It does not mention when not to use it or name sibling alternatives such as get_balance, so it stops short of a full exclusion list.

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