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

readOnlyHint=true already tells the agent this is a safe read, so the bar is lower. The description adds behavior beyond the annotations: it discloses the returned field set and the default cross-partition query-and-merge semantics. It stops short of describing pagination or result-size limits, so it is strong but not exhaustive.

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 sentences, front-loaded with the verb+resource, then returns, then routing guidance, then the partition nuance. No sentence is redundant with another, and the most decision-relevant information (what it returns and when to call it) comes early.

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 compensates by naming the returned fields, and with readOnlyHint covering safety and 100% schema coverage on parameters, there is little left unstated. An agent has what it needs to resolve a site reference and route the siteId into a sibling 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?

Schema description coverage is 100%, so the llm_model and conversation_id parameters are fully documented in the schema and the baseline is 3. The description adds meaning beyond the schema for `partition`: it clarifies that the default is to query all partitions and merge the results, whereas the schema only says 'omit to query all partitions'.

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 (List) and resource (Hostsmith sites) scoped to the user's account, and enumerates the exact fields returned (siteId, subdomain, domain, status). It also names the downstream siblings that consume siteId (get_site, deploy_files, deploy_create_upload, delete_site), so an agent can distinguish it from any other listing tool without opening a 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?

Explicitly prescribes when to call it: 'call it before any create/deploy/delete to resolve the user's site reference', and frames it as 'the source of truth for does the user already have a site at FQDN X'. That is a clear precondition tying it to the create_site/deploy_*/delete_site siblings rather than leaving usage to inference.

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