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

With no annotations, the description carries the full burden, and it does add real behavioral context: prices are live, are quoted before VAT, and default to GBP. It is silent on read-only status, auth/rate-limit requirements, and whether results are paginated, so the safety and access profile remains undisclosed.

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 tight sentences, front-loaded with the resource and what it returns, then the parameter behavior. No filler or repetition of the tool 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 single-optional-parameter listing tool with no output schema, the description covers return content (live prices, resources, config options, add-ons) and the parameter well. Pagination/result-size behavior is the only notable omission, which is minor for this kind of catalog call.

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 coverage is 0%, so the description must compensate, and it largely does: it marks the currency as optional, lists six allowed ISO codes, and states the GBP default. The only gap is ambiguity over whether codes outside the listed six are accepted, which slightly undercuts the enumerated list.

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?

It gives a specific verb (List) and resource (UmbHost buyable Umbraco hosting/email plans) and enumerates what the listing includes (prices, resources, config options, add-ons), which makes the tool's scope unambiguous. It does not, however, explicitly differentiate itself from the sibling get_plan or quote, leaving the list-vs-single-plan distinction 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?

Usage is only implied: a plan-listing tool is naturally the browse step before get_plan/begin_checkout, and it notes prices exclude VAT, but there is no explicit when-to-use, when-not-to-use, or named alternative. An agent gets a reasonable sense of context but nothing that routes it decisively among the six siblings.

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