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

Annotations only declare the mutation/safety profile (readOnly=false, idempotent=false, destructive=false); the description goes well beyond by disclosing the redirect from the old address, that the old name stays reserved and the rename can be reversed, and an explicit inventory of what carries over (pages, history, statistics, custom domains, forms, editors, GitHub publishing). This directly substantiates the non-destructive annotation rather than restating it.

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?

Four short sentences, front-loaded with the action and then the consequences, with no filler or repetition. Each sentence carries distinct information: what happens to the address, reversibility, state that carries over, and the human confirmation step.

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 does the necessary work of explaining post-call state (new address live, old address redirecting, old name reserved), so an agent can report results accurately. It does not address failure modes such as the new name already being taken by another site, nor whether the rename is immediate, which are the remaining gaps for a mutation tool.

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 new_name parameter is already fully documented in the schema (length, character set, no dots, resulting address format), and the description's added value there is consequence-level (address changes, old address redirects) rather than syntactic. The site parameter has no schema description at all and the description only says it must be a site you own, leaving its expected form (name vs. identifier) unstated at 50% coverage.

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?

Opens with a specific verb+resource ("Rename a site") plus an ownership qualifier ("you own"), which cleanly separates it from siblings like create_site, delete_site, and transfer_site. An agent can identify the operation and its target without consulting the schema.

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?

Gives a clear precondition (the site must be one you own) and a procedural instruction to confirm the new name with the person first, which is genuinely useful for a mutation tool. It does not name alternatives (e.g., create_site for a fresh site, transfer_site for ownership moves), so it stops short of full when/when-not routing.

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