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

Annotations are absent, so the description must carry the full behavioral burden. It describes returned content but says nothing about authentication, side effects, rate limits, or whether the call is read-only. The only behavioral pointer is to a separate accept 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 short sentences, front-loaded with the tool's purpose and immediately followed by the next step. Every word earns its place and there is no redundancy.

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 no-parameter list tool with no output schema, the description gives the essential content and a next action. However, it omits any differentiation from the similar-sounding 'open_fights' and provides no behavioral context, leaving the agent to infer safety and prerequisites.

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?

The tool takes no parameters, so the schema provides no parameter details to miss. Per the rubric, zero parameters baseline to 4; the description appropriately adds no parameter information because none is needed.

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 clearly identifies the resource—fighters waiting for an opponent right now—so an agent knows what data is returned. However, it lacks an explicit verb and does not distinguish itself from the sibling 'open_fights', which could be a similar listing.

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?

It implies usage by naming the next action ('Accept one with prepare_accept'), giving an agent a clear path after finding a challenge. But it offers no guidance on when to choose this tool over alternatives like open_fights or prepare_challenge, and no exclusions.

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