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

Strong for a tool named "check": it discloses that confirmation is a mutation that applies sending credits or activates prepaid domain hosting exactly once, with no human checkout, and that it requires the caller's API key. This adds real context beyond the annotations (readOnlyHint=false, idempotentHint=true) by explaining what the write actually does and why idempotency matters.

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 with the primary action first and the side-effect/auth caveats following. No filler, though the phrasing "applies sending credits or activates prepaid domain hosting once" is dense and could be split for clarity.

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 side-effecting tool with zero schema description coverage and no output schema, the description omits what the check returns (payment status? invoice state?) and never defines the token. Auth and side effects are covered, but the caller still cannot predict the response or the parameter's valid values.

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% for the single required "token" parameter, and the description never explains what the token is (an invoice token? a payment token? where it comes from). The phrase "this account's" hints at account scoping via the API key, but the parameter's meaning and format remain undocumented.

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?

"Check this account's native USDC invoice" names a verb and a resource, but it is ambiguous what is actually being checked (status? existence? amount?) and what the token represents. It is distinguishable from check_balance and check_sending_status only by the word "invoice"; no sibling is named.

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?

No statement of when to call this versus create_payment or check_sending_status, and no preconditions beyond "Requires the same account's API key." The mention that confirmation activates credits/hosting implies a decision point, but the caller is never told which condition triggers which outcome.

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