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

Annotations already declare destructiveHint=true and openWorldHint=true; the description adds genuinely non-structured context: auth requirements, a hard PCI constraint ('Never send PAN/CVV'), per-purpose minimums, and a caveat that the key environment does not select the Square sandbox. It never explains why the operation is flagged destructive or whether a created link can be cancelled, which is the main remaining 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?

Dense, front-loaded, no filler: purpose first, then auth gate, then constraints. The final sentence about the key environment and Square sandbox is terse to the point of being hard to parse, but nothing is wasted.

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 destructive, non-idempotent payment-link creation with an output schema, the description covers auth and input constraints but says nothing about the created link's lifecycle (expiry, reuse, cancellation) or when to prefer the sibling purchase_credits. An agent has enough to invoke it, but not enough to reason about side effects.

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% and the amountCents description in the schema already states the 100-cent and 1-cent minimums, so most of the description's parameter detail is repetition. The one contribution is tying the minimum to the purpose enum, but returnPath semantics are left entirely to the schema.

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+resource+mechanism: creates a Square hosted Payment Link to fund an authenticated workspace, which is clearly more than a restatement of the name. It does not, however, distinguish itself from the sibling purchase_credits, which an agent will likely see as competing for the same intent.

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 clear context and prerequisites: requires a workspace Bearer key or OAuth, and unauthenticated checkout is unavailable. It also excludes a nearby assumption ('Does not send mail'). It stops short of naming alternatives such as purchase_credits or inspect_credit_payment for follow-up.

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