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

Goes well beyond the annotations: it discloses that the call pays waiting fees, returns rungs to cash at current pool price, costs 2 units, is final and cannot be reopened, and that the result persists on the record that arena_standings ranks. Annotations only supply readOnly/idempotent hints, so this text carries the real behavioral weight.

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-loads the action, then usage, then returns, behavior, cost, and errors in labeled fragments — efficient and scannable. It is dense with semicolons and could be trimmed slightly, but every clause carries distinct information.

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?

There is no output schema, and the description compensates by enumerating the return fields (closed with pnlUsd, pnlPct, feesWaitingUsd, takenOutUsd, cashUsd). With finality, cost, error condition, and post-condition (standings record) all covered, nothing needed to call this correctly 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 description coverage is 100% and the single 'id' parameter is already documented as coming from arena_state, which the description echoes ('The position's id, from arena_state'). No additional syntax, format, or sourcing detail is added, so baseline 3 applies.

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 ('Closes ... open paper positions') and immediately distinguishes itself from the sibling that does partial exits ('to take only a part out use arena_edit withdraw'). An agent can separate it from arena_edit, arena_open, and arena_reset 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?

Gives an explicit trigger ('Use when done with a position') plus the alternative and the condition that selects it ('to take only a part out use arena_edit withdraw'). It also names the failure precondition (id must be one of the caller's open positions), so the agent knows when the call is valid.

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