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

With no annotations, the description carries the full behavioral burden. It usefully discloses the null-on-unknown-key behavior, but says nothing about read-only semantics, whether currency conversion is applied, error handling beyond null, or rate limits.

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 with no filler, front-loading what the tool returns and ending with the important null edge case. Every clause earns its place.

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 and no annotations, the description does the needed work of enumerating what comes back (per-cycle prices, config options, add-ons) and covers the unknown-key case. It falls short only on the currency parameter, which is left unexplained.

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 0% for 2 parameters. The description clarifies that "key" identifies a plan, but the "currency" parameter is never mentioned in text and has no schema description, leaving its meaning and allowed values completely undocumented.

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 ("Get one UmbHost hosting plan") and scopes it to a single item by key, which implicitly contrasts with the sibling list_plans. However, it never names list_plans or quote, so sibling differentiation is left to inference rather than made explicit.

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: the caller is expected to already have a plan key. There is no explicit when-to-use guidance relative to siblings like list_plans (browse) or quote (price an order), and no exclusions or prerequisites are stated.

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