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

Annotations already cover read-only, idempotent, and non-destructive behavior, so the description only needs to add context. It adds account-level scope and the 'currently available' dynamic aspect of the value, which is useful; auth or rate-limit details are not needed for this simple quota read.

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 a single 14-word sentence with the verb front-loaded and no filler. Every word adds meaning, and it does not repeat annotation content.

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 parameters and no output schema, this description still provides the essential contract: the return value is a count of URL checks currently available on the account. For a simple zero-parameter quota tool, nothing necessary for correct invocation is missing.

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?

The tool takes zero parameters, so baseline 4 applies. There is no parameter detail the description needs to compensate for, and the text introduces no parameter ambiguity.

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 uses a specific verb ('Returns') and names the exact resource: the number of URL checks available on the account. This separates it from the job- and domain-focused siblings, so an agent can tell get_usage from get_job_results, get_job_status, and get_verified_domains.

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 explicit statement about when to call this tool or when to choose a sibling instead. The sibling names and the word 'available' imply a quota-check use case, but the description leaves that inference entirely to the agent.

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