Is this address free?

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

readOnlyHint and openWorldHint already carry the safety profile, and the description adds genuine context: that this is a pre-flight availability check and that the label becomes the user-visible shared URL. It does not say what a taken label looks like in the response, whether labels are globally unique, or whether checking reserves anything — gaps that matter for an agent deciding what to do next.

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?

Two sentences, zero filler, with the action and the resulting address front-loaded and the workflow hint second. Nothing repeats the title or the schema.

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 single-parameter read-only check with no output schema, the description covers purpose, timing, and what the label denotes. The only meaningful omission is the shape/meaning of the answer (free vs. taken), which the agent must infer from 'check whether ... is free'.

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, but the description goes beyond the schema's 'The label to check, like my-app' by explaining that the label is the subdomain portion of my-app.antideploy.app and that it is user-chosen. That mapping adds real meaning an agent would otherwise have to infer.

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 and resource ('Check whether an address label ... is free') and immediately gives the concrete form the label takes (my-app.antideploy.app). The 'before creating the application' framing separates it cleanly from create_application without ambiguity.

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?

Explicitly places the tool in a workflow: call it before creating the application with that label, which implicitly routes the agent to create_application afterwards. It stops short of stating exclusions (e.g., whether to call it on redeploy or on an existing link), so it is clear context rather than a full when/when-not rule.

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