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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered elsewhere. The description adds no behavioral context beyond the annotations: nothing about what qualifies as a rivalry, whether results are ranked or limited, or how the single-team versus paired mode differs in output. An output schema exists, so return format need not be explained, but the remaining behavioral surface is untouched.

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?

A single front-loaded sentence with no filler or redundancy. It is efficient, though its brevity is partly the source of the gaps noted in other dimensions rather than pure economy.

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?

With four undocumented optional parameters, a zero-coverage schema, and an all-null default state, the definition leaves the agent guessing about valid argument combinations and default behavior. The presence of an output schema relieves it of return-value explanation, but the input-side ambiguity is substantial for a tool of this shape.

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% across four parameters, so the description carries the full burden and only partially discharges it. It hints that team_id/team_name are used for the one-team mode and opponent_id/opponent_name for the two-team mode, but never explains id-versus-name precedence, whether both can be supplied, or the effect of leaving everything null.

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 names a specific verb and resource ("Get rivalries") and distinguishes two retrieval modes: rivalries for one team, or between two teams. No sibling tool deals with rivalries, so no differentiation is required, but the two-mode framing is stated clearly enough that an agent understands the scope.

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 phrase "for a team, or between two teams" implies the two intended invocation shapes, but the description never maps them to parameters or states what happens when no arguments are supplied, which is a real concern given that all four parameters are optional. Usage is inferable but not explicitly guided.

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