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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the safety profile is known; the description still adds the concrete consequence ("voids it") and the auth requirement, which are useful beyond the flags. It does not cover idempotency (annotation says false) or side effects on the opponent/rating, so it stops short of full disclosure.

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?

Front-loaded with purpose, then WHEN, then alternative routing, then auth, then a call example — every fragment carries information and there is no filler. Typical of a well-formed short tool definition.

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?

An output schema exists so return values need not be explained, and auth plus the destructive consequence are covered. Minor gaps remain: whether the match must be active, and what forfeiting does to standings or the opponent.

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 100% and all three parameters are documented in-schema, so the baseline is 3. The description adds only a concrete call example for match_id, no additional semantics for key or guest_token beyond what the schema already states.

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 verb and resource ("Forfeit match") and immediately clarifies the effect ("give up your active match (voids it)"), which is more than a restatement of the title. It differentiates from arena_act's FORFEIT move, though it says nothing about the nearby sibling arena_end_match, leaving one plausible ambiguity.

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?

Explicitly names an alternative ("Prefer this over arena_act {move:\"FORFEIT\"} when you just need to exit") with the condition that selects it. It gives clear positive usage context but no exclusion against arena_end_match, the other seemingly adjacent sibling.

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