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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is fully covered. The description adds the source URL and explains the case conversion semantics, but doesn't disclose details like how 'title' handles edge cases (e.g., articles, hyphenated words) or how 'sentence' detects sentence boundaries. For a pure text transformation, this is adequate but not rich.

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 a single compact sentence that front-loads the core purpose, then defines all four modes in a scannable list, and ends with a source attribution. Every element earns its place with no wasted words.

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 simple two-parameter text transformation with an output schema, the description covers the essential semantics. The mode definitions are the only real ambiguity, and they are fully explained. The source URL is a minor bonus. It doesn't discuss edge cases, but for this tool's simplicity, the description is complete enough for an agent to invoke it correctly.

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%, so both parameters ('text' and 'mode') are already documented in the schema. The description adds value by explaining what each enum value does, which goes slightly beyond the schema's terse 'The target case' description. However, the schema already carries the parameter definitions, so the description's contribution is marginal.

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 clearly states the tool converts text to a different letter case, and explicitly defines each of the four modes ('upper', 'lower', 'title', 'sentence') with examples. This is a specific verb+resource that distinguishes it from the many other text-manipulation siblings like hopi_reverse_text or hopi_remove_extra_spaces.

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 explains what each mode does, which effectively tells the agent when to use this tool and which mode to select. It doesn't explicitly name alternatives or exclusions, but the mode definitions provide clear context for choosing this tool over other text utilities. The sibling list contains many text tools, but the description's mode breakdown is sufficient guidance for this simple utility.

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