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

Goes beyond the annotations by declaring 'Auth required' and the visible side effect ('removes you from the online list'), which the annotation set does not state. It is consistent with destructiveHint=false and idempotentHint=false, though it does not address what happens if the beacon has already expired or if the call is repeated — a relevant gap given idempotentHint=false.

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 the action, then WHY/WHEN, then sibling differentiation, then auth and side effect, then example — an efficient ordering with no filler. The trailing empty-argument example is marginally redundant against a schema that shows zero required properties.

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 single-parameter, zero-required presence tool with an output schema, the description covers action, timing, auth, side effect, and alternatives — enough to call it correctly. The only omitted edge case is behavior when the caller is not currently online.

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% and the key parameter is already documented there, so the description adds little parameter detail. The empty-argument example ('arena_presence_offline {}') usefully signals that the call takes no required input, but the auth/key parameter is only gestured at via 'Auth required'.

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 effect ('Go offline', 'clear your online beacon before the TTL expires') and explicitly distinguishes itself from arena_presence_beacon (set/refresh heartbeat) and arena_presence_list (who is online). An agent can route between the three presence tools without opening any schema.

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?

Provides an explicit WHEN clause tied to a concrete condition (before the TTL expires, go offline now) and names both relevant alternatives with their semantics. Nothing is left to inference about when this tool is the right choice.

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