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

Beyond the annotations (which already declare a non-read-only, non-destructive, non-idempotent write), the description adds real context: the return payload, the plan-based quota ceiling, and the auth requirement with the caveat that Free keys suffice. It stops short of saying what happens when the limit is exceeded (error vs. silent failure) or noting that retries create duplicates.

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 short sentences with zero filler: the action and outputs come first, then the quota constraint, then the auth requirement. Each sentence carries distinct, actionable information.

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 output schema, the description correctly compensates by naming the returned site key and install snippet, and it covers quota and auth for a mutation tool. The main remaining gap is failure behavior when the plan limit is hit or the domain is already taken.

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%, with both name (max 60 chars) and domain documented in the schema itself, so the baseline is 3. The description adds no further meaning about the parameters, such as domain format constraints or whether the domain must be unverified/unique.

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 ("Creates a site in the user's account") and names the concrete outputs (site key and install snippet), so it is clearly distinguishable from read-only siblings like list_sites and check_install. It does not, however, explicitly address the overlap with get_install_snippet, which also deals with the snippet.

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?

Usage is implied by "Creates" and constrained by "Respects the plan's site limit (Free: 1 site)", which tells the agent when the call will be rejected. There is no explicit when-to-use versus alternatives guidance (e.g. use get_install_snippet to re-fetch the snippet later rather than re-creating).

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