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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the mutating/irreversible nature is flagged. The description adds the double-payment protection rationale for idempotency_key, but that same fact is already stated in the schema field description, and it says nothing about permissions, the payout-destination precondition, or what happens when no destination is active.

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?

Two tight sentences with the core action front-loaded and the idempotency advice second; nothing extraneous. The second sentence slightly duplicates the schema's idempotency_key text, which keeps it just below a 5.

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 3-parameter money-movement tool with no output schema, the description covers the destination and retry semantics but omits the required precondition (active payout destination), the fact that no parameter is marked required, currency behavior, and any failure mode. Annotations carry the safety profile, but the operational context is thin.

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 67%: amount and idempotency_key are documented in the schema, while currency is undocumented in both places. The description only reinforces idempotency_key, which the schema already explains, so it adds little parameter meaning beyond the structured fields — baseline 3.

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 ('Withdraw earnings to the account's payout destination'), which clearly separates it from read siblings like get_withdrawal and list_withdrawals and from the unrelated withdraw_bid. It does not explicitly reference the sibling read tools or explain the 'Legacy' qualifier from the title, so it stops short of full sibling differentiation.

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 gives no when-to-use guidance, no mention of the prerequisite that an active payout destination exists (that only appears in the title), and no pointer to setup_payouts or payout_status as alternatives. An agent must infer the context entirely.

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