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

Annotations already declare readOnlyHint/idempotent/non-destructive, and the description adds real value by enumerating the returned fields and setup-type values, which is the only source of return-shape info since there is no output schema. Minor gap: no mention of pagination or behavior for accounts with zero provisioned sites, but the trailing 'Read-only' confirms rather than contradicts the annotations.

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 sentences with strict front-loading: payload first, invocation triggers second, safety note last. The quoted user phrasings are compact and each directly earns its place as a routing cue.

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 zero-parameter, read-only list tool with no output schema, the description supplies purpose, returned fields, and trigger contexts — everything an agent needs to select and call it. The annotations carry the safety profile, so nothing material is missing.

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 tool takes no parameters (empty object schema), so there is nothing for the description to disambiguate. Baseline 4 applies; nothing is gained or lost here.

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 ('Returns the list of hosting sites the customer has provisioned') plus the exact payload fields (panel URL, setup type, Plesk login). This clearly separates it from nearby siblings like list_my_domains, get_hosting_catalog, or get_my_site_runtime.

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 concrete trigger phrasing ('what sites do I have?', 'where do I log in to my hosting?', 'what's my hosting panel URL?'), which is strong routing signal. It stops short of naming alternatives or exclusions (e.g., when to prefer get_hosting_catalog for purchasable plans), so it lands at clear-context-but-no-exclusions.

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