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

Annotations already declare readOnlyHint=true and idempotentHint=true, and the description adds valuable behavioral context: hero skill restrictions at account level, the PvE-only skill prohibition including Signet of Capture, and how validate_build reports violations. This goes beyond the annotation baseline and is directly useful for downstream build validation.

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 sentences, each with a distinct job: core lookup, return summary, important domain caveat, and sibling routing. The description is front-loaded with the primary action and avoids redundancy with the schema or annotations.

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 read-only lookup tool with optional parameters, an output schema, and a clear sibling alternative, this description covers everything needed to select and invoke the tool correctly. It explains the identifier source, what data is returned, a critical hero-skill rule, and when to use list_heroes instead.

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% and both parameters are documented, so the baseline is 3. The description adds extra meaning by clarifying that the id is a GWCA HeroID matching AccountExport plugin output, which helps an agent supply the correct value. It also reinforces the name-or-id duality, though the schema already captures this.

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 and resource: 'Look up a GW1 hero by name or by id.' It also names the distinct identifier format (GWCA HeroID) and explicitly differentiates itself from list_heroes, so an agent can distinguish this tool from its siblings without opening schemas.

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 routing guidance: 'Use this for one known hero; to browse or filter the roster, use list_heroes instead.' It also warns about validate_build behavior with forHero=true, giving clear context for when this lookup result matters downstream.

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