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

Annotations already declare readOnlyHint, openWorldHint=false, and destructiveHint=false, so the safety bar is low. The description adds specific behavioral context beyond that: "no send or trial activation," which tells the agent this call has no downstream side effects. It also notes localization metadata is returned, though the output schema covers that.

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 tight sentences with the core purpose front-loaded; nothing is buried or padded. The closing "Read-only" clause partially restates the annotations, which is mild redundancy but is paired with the non-duplicative "no send or trial activation" detail.

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, read-only lookup with an output schema present, the description covers purpose, timing, parameter effect, and side-effect profile. Return values need not be explained given the output schema, so nothing essential 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?

Schema coverage is 100%, so the baseline is 3. The description goes further by stating the parameter is optional and explaining its effect — selecting uiLanguage localizes the returned labels — which clarifies intent beyond the schema's format-only description.

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 — listing Poly-Glot's supported languages — with the additional scope detail of UI, input, and AI output categories and the count (38). This clearly separates it from siblings like localize_text, translate_text, and detect_language, which perform work in a language rather than enumerating available languages.

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?

"Use to verify language availability before multilingual work" gives a clear context for invoking the tool. It does not name a specific alternative to use instead, nor state any exclusions, so it falls short of a full when/when-not/alternatives statement.

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