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

With no annotations, the description carries the behavioral burden and does disclose useful traits: it returns 'real default, accepted values, description, and CSS variable (design keys only)' and gives a 'fuzzy-matched suggestion' for unknown keys. It stops short of explicitly stating side-effect safety or authentication needs, though 'looks up and returns' strongly implies a read-only operation.

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?

The core behavior is front-loaded in a single tight sentence. The second sentence is a bit dense with two alternatives, but every clause carries routing information and no filler is present.

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 one-parameter lookup tool with no output schema, the description covers what is returned, how unknown keys behave, and how the tool relates to install and account-management alternatives. It could add explicit error/edge-case behavior, but the essential operational context is present.

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 the property description already states that 'key' is 'A huOptions.design.* or huOptions.text.en.* key to explain.' The tool description repeats the same constraint without adding examples, formatting rules, or deeper meaning, so it adds no value beyond the schema.

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?

The description opens with a specific verb and resource ('Looks up a huOptions.design.* or huOptions.text.en.* key') and enumerates concrete return values (default, accepted values, description, CSS variable). It also names alternatives (install.getSnippet, account.*) that are outside its scope, so an agent can distinguish it from siblings.

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?

It explicitly writes 'To install the banner on a site use install.getSnippet' and 'to change the settings of a REAL registered banner, the account.* tools need an authenticated connection — call help.explainTokenSetup.' This gives clear when-not-to-use routing while the first sentence establishes when to use this tool for key lookup/explanation.

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