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

Annotations already disclose read-only, idempotent, and non-destructive behavior. The description adds valuable context by listing supported entity types (named and numeric) and the conversion direction, which goes beyond what annotations provide. It does not mention edge cases like unknown entities, but this is acceptable for a simple conversion tool.

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 concise sentences: the first states the action and entity list, the second gives usage context. No filler or redundancy; all information 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?

For a simple one-parameter tool with a clear schema, annotations, and an output schema (as signaled), the description covers purpose, usage, and example entities. It lacks explicit mention of handling invalid HTML entities or recursion, but those are edge cases unlikely to block correct invocation.

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?

Input schema fully describes the single parameter 'input' as 'HTML-encoded string to unescape'. The description does not add further parameter-specific details beyond the schema, so the baseline of 3 applies.

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 'Convert' and a clear resource: HTML entities. It enumerates the exact entities handled (&, <, etc.) and contrasts with counterpart tools like escape_html by stating it converts 'back to plain characters'. This clearly distinguishes 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?

Provides explicit when-to-use context: 'when processing HTML-encoded text from APIs, email content, or legacy database fields before passing to an LLM or displaying to users.' It does not mention when-not-to-use, but the guidance is clear enough for selection among sibling tools.

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