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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavioral information in 'Costs 2 credits,' which is not expressed anywhere in the structured fields; it does not, however, say whether credits are charged on an invalid event_id or an empty card.

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: usage cue first, then the return inventory, then the cost. Every clause carries information an agent would otherwise have to guess.

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?

Only two parameters and an output schema exists, so return shape needn't be described, yet the description still summarizes the payload and adds the credit cost. Nothing material for correctly invoking this read-only fetch is missing.

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%: event_id is documented as coming 'from list_events or get_schedule' and league carries its enum plus the mma default. The description adds nothing about either parameter, so the baseline 3 applies – the schema does all the work.

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 concrete verb+resource ('Use for one card') and enumerates exactly what comes back: every fight in order with result, method, round, time, judges' scores and referee. This implicitly separates it from get_fight (single bout), but it never names a sibling, so differentiation is left to inference.

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?

'Use for one card' is a usage directive that hints at the whole-card vs single-fight split with get_fight, but no alternative tool is named and no when-not condition or prerequisite is stated. An agent must infer the routing from the sibling names.

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