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

No annotations exist, so the description carries the full burden. It discloses the dual behavior and a pricing/quota footnote ('5 free trial calls per signed wallet'), but says nothing about auth/wallet requirements for calls beyond the trial, whether it is a read-only operation, error behavior, or output format. Compare to the MID calibration where an un-annotated tool scored 2.

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?

A single front-loaded sentence delivers the core purpose, with the trial/pricing note appended compactly. Slightly promotional (emoji/free-trial tag) but not wasteful.

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?

With no annotations, no output schema, and two undocumented parameters, the definition leaves too much open: which parameter to pass, what a scope explanation looks like, and what a caller needs (wallet/payment) beyond the free trial. For an agent to invoke this reliably, more is needed.

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 0% for two parameters. The description addresses only 'scope' (and its omitted-value behavior) and leaves the 'input' parameter entirely unexplained, so it is ambiguous which field carries the scope name and what the other is for. It does not compensate for the coverage gap.

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+resource ('Explains one OAuth scope name') and covers the no-argument mode ('lists the built-in scope descriptions'). It is clear about what is produced, though it doesn't name or differentiate from any sibling (none of the ~800 siblings covers OAuth scopes, so that is less costly).

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?

The description distinguishes the two invocation modes (scope supplied vs. omitted), which implies how to call it, but it gives no when-to-use/when-not guidance, no prerequisites, and no alternatives. Usage must be inferred from behavior rather than stated.

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