Compatible supports

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

With only readOnlyHint in annotations, the description adds meaningful behavior: results are ranked by the game's own recommendations first then tag matches, each result explains its rationale, and lineage supports are flagged as rare/expensive drops. That's real value beyond the annotation, though it doesn't describe output shape or result limits.

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?

Three short sentences, front-loaded with the core function followed by ranking behavior and one caveat. No filler or repetition of the name.

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?

No output schema exists, and the description notes each result 'explains why,' partially compensating. For a read-only lookup with a 4-param schema, an agent has enough to call it correctly; only return-format detail is thin.

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 75% and documents gemId, prefer, and includeLineage individually. The description adds interpretation the schema lacks: the 'game's recommendations first, then tag matches' ordering clarifies what 'prefer' actually does, and the lineage cost note explains why includeLineage matters.

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?

States a specific resource (support gems) and its relation to the input (gems that can support a given skill), plus the ranking logic. This is clearly distinguishable from siblings like search_skills and gem_details, which operate on skills/gems rather than supports.

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 implies you use it after identifying a skill to find its supports, but it never states when to prefer this over siblings (e.g. suggest_extras) or any prerequisites. Usage is inferable from context rather than explicit.

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