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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds non-redundant behavioral context: regex is case-insensitive, only a 'safe subset' of regex is supported, and the response is 'lightweight metadata.' This goes beyond the structured annotations and helps set expectations about matching behavior and return payload.

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 four sentences with zero wasted words. The primary purpose is front-loaded, followed by the usage condition and key behavioral nuances. Every sentence contributes meaningful information, and the structure is easy to scan.

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 list tool with safe annotations, the description covers purpose, usage context, regex behavior, and return weight. It does not detail pagination semantics or what 'lightweight metadata' contains, but the schema defaults and the tool's simple nature make this a minor gap. Overall, an agent has enough to select and correctly invoke the tool.

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 0%, so the description carries the burden of explaining parameters. It clarifies the hero_regex parameter by noting it is a regex, case-insensitive, and restricted to a safe subset. However, the optional page and page_size parameters are not explained in the description, leaving their semantics to inference from names and schema constraints. The main parameter is covered, but not all parameters.

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 states a specific verb ('List') and resource ('Heropedia Hero/Role entries'), and narrows the scope by the matching criterion ('Hero name matches the supplied regex'). It also distinguishes this from siblings by emphasizing hero-based lookup versus role-based lookup, so an agent can tell it apart from getListByRole.

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 explicitly says 'Use when you know or can identify the Hero and want to inspect that Hero's available Roles,' giving a clear condition for when this tool is appropriate. It does not explicitly name alternatives or say when not to use it, but the sibling context and the clear when-to-use clause provide sufficient guidance.

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