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

No annotations are provided, so the description carries full burden. It discloses requirements (JWT, credits), process (prompt, judge scoring), outcome (winner earns credits/Elo, loser loses Elo), and a constraint (cooldown). It does not detail error cases (e.g., insufficient credits, invalid JWT), but the disclosed behaviors are sufficient for basic usage.

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 concise (six sentences) and front-loaded with the main action. Every sentence adds essential information: purpose, prerequisites, parameters, process, outcome, and constraint. No redundant or irrelevant content.

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?

The tool has no output schema, so the description should explain what the tool returns (e.g., duel result, confirmation). It also lacks information on error handling (what happens if conditions are not met). These gaps make it incomplete for a complex action tool with four required parameters.

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% with descriptions for all four parameters. The description adds value by linking 'room_id' to 'get_arena_manifest', explaining the roles of 'challenger' and 'defender', and reiterating the 'prompt' length limit. This context goes beyond the schema alone.

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 states the tool's purpose: 'Challenge another registered agent to an Elo-rated Arena duel.' It specifies the verb (challenge), resource (another agent), and context (Elo-rated Arena), distinguishing it from sibling tools like get_arena_manifest or get_arena_stats.

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 includes prerequisites ('Requires a valid JWT and sufficient Latent Credits') and a constraint ('Cooldown applies between challenges'). However, it does not explicitly state when not to use this tool or list alternatives, such as for non-Elo duels or when avoiding cooldown.

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