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

Adds real behavior beyond the annotations: the reservation is time-boxed to a day, the site is not live until payment at Stripe, and a second call replaces the pending address. That replacement trait is the key non-obvious consequence, consistent with idempotentHint=false and destructiveHint=false. It stops short of saying what happens to an already-active site or what the response contains.

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, each carrying distinct information: what it does, when the next call is needed, and the one-at-a-time replacement rule. Nothing is redundant with the title or name.

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 two-parameter creation tool with no output schema, the description covers the reservation window, the payment dependency, and the replacement semantics, which is what an agent needs to sequence calls. Minor omissions: what a successful call returns and whether an existing active site is affected.

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 (site, name) are documented in the schema, including the jane.pixelglass.me example. The description adds no extra syntax, validation, or format constraints, so it meets but does not exceed the baseline.

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 with scope: 'Reserves a site address for this account for a day.' It also marks the boundary with the adjacent sibling by naming start_checkout as the separate step that actually starts the site, so an agent can tell it apart from site_status or start_checkout.

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 an explicit next step ('call start_checkout next') and a clear constraint on repeated use ('One address waits at a time; a second replaces the first'). The only gap is that it never names an alternative for other site-management actions (list_sites, site_status), though the sequence guidance is unusually concrete.

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