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

Annotations already declare non-read-only, open-world, non-idempotent behavior, so the bar is lower. The description still adds real context beyond them: authentication via API key or OAuth token, an emailed verification code, and the fact that changes are provisional until partner_confirm_payout. It does not say whether an existing payout method is overwritten, which is the main remaining behavioral gap.

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?

The text is front-loaded with the authentication requirement and then condenses ten parameters into groupings without repeating the schema verbatim. It is dense, using semicolons and parentheticals, but nearly every clause carries information an agent needs. Slightly more separation between the method enumeration and the confirmation step would improve readability.

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 10-parameter mutation with 10% schema coverage and no output schema, the description is respectably complete: it covers auth, the type-to-field mapping, and the deferred-effect flow. It still omits what happens to an existing payout method, error/validation behavior, and whether the email code is passed to this tool or to partner_confirm_payout.

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 only 10% (only 'type' is documented), so the description must compensate, and it largely does: it maps paypal to paypal_email, the crypto types to address with network-specific meanings for usdc_base/usdc_solana/eth/sol/btc, and bank to holder, country, currency, iban or account_number, and bic or routing_number. This resolves the conditional-field puzzle the schema leaves open. Formats (IBAN/address syntax) are still unexplained, preventing a 5.

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?

The description plus title make clear this tool registers a payout destination, and it enumerates the three method families (paypal, crypto, bank) with their required fields. It also distinguishes itself from the sibling partner_confirm_payout by stating that the details only take effect after that call. It stops short of a single explicit 'sets the partner's payout method' verb sentence, which keeps it off a 5.

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?

Usage is implied by the payout-method framing and the sequencing note about partner_confirm_payout, so an agent can infer the two-step flow. However, it never states when to call this versus partner_confirm_payout, nor any prerequisites such as whether an existing method is replaced or whether the account must already be a partner. There are no explicit exclusions or alternatives.

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