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

Annotations already declare readOnlyHint and idempotentHint, so the safety profile is covered. The description adds useful behavioral context beyond annotations: that the call is 'Free', that protected translation covers Hebrew, English and Russian, and what fields are returned.

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 description is compact: two sentences that front-load the core operation, then list the returned fields and relevant constraints. No filler or repetition of the schema exists.

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 parameterless listing tool with an output schema and safety annotations, the description fully covers what the tool does, what it returns, and how the output is meant to be used. 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?

With zero parameters and 100% schema coverage, there is nothing for the description to document. It still clarifies how the returned language codes relate to tool parameters, which is a helpful semantic addition.

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 names a specific action and resource: 'List every language HebrewCore translates to and from.' It specifies the exact fields returned (code, English and native name, writing direction), which clearly defines the tool's purpose and distinguishes it from translation and detection 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?

The description gives practical usage guidance by noting the code can be used as `source_lang` / `target_lang`, which tells the agent how the output feeds into other tools. It does not explicitly exclude alternatives, but the tool is a unique listing operation and no sibling competes with it.

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