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

Annotations already declare readOnlyHint=false and openWorldHint=false, so the mutation and closed-world profile is known. The description adds a useful detail beyond that — the creation returns a site_key and a tracking script — but says nothing about whether the domain must be unique, what happens on duplicate submission, or whether the call is idempotent.

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 short sentences with zero filler; the action is stated first and the return value second. Nothing could be removed without losing 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?

For a simple two-parameter creation tool with full schema coverage, the description covers the action and the key return values, which is close to sufficient. It falls short on mutation-side risks — domain uniqueness, failure modes, and what the agent should do with the tracking script — which matter for a create operation.

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 100% and both parameters (name, domain) are documented in the schema, including the default-to-domain behavior for name. The description adds no parameter-level meaning beyond that, so the baseline of 3 applies.

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 ("Add a site") plus what it returns ("site_key and tracking script"), which is more than a restatement of the title. It does not, however, explicitly distinguish itself from siblings like list_sites or get_site_analytics, leaving the creation-vs-read split to be inferred from the verb.

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 when-to-use guidance, no mention of prerequisites (account/auth, plan limits), and no reference to any alternative tool. The agent must infer from the verb alone that this is the entry point for onboarding a property.

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