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

Annotations already cover readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is largely provided. The description still adds value by disclosing returned fields (merchant, callerPays, expiry, payability, supportedSources) and the constraint that native coins are only valid when listed in supportedSources, plus an explicit 'creates nothing and moves no funds' statement.

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?

Purpose and return values are front-loaded, and the routing rule plus the create_deposit_order distinction each earn their place. The middle enumeration of returned fields is slightly dense, but there is no filler.

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?

With no output schema, the description carries the burden of describing return values and does so explicitly. Combined with the annotations and full schema coverage, an agent has everything needed to call this tool correctly and interpret its output.

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 url parameter is fully documented there with examples and maxLength, so the schema does the heavy lifting. The description adds only 'takes the link URL', which restates the schema without new format or edge-case detail — the 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 (quoting a Coinbase invoice / payment link) and enumerates precisely what it answers: charges, payability, and payable coins. It also names the sibling create_deposit_order as the source of exact per-coin amounts, so an agent can distinguish the two without opening either 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?

Clear context for use (inspect a payment link before paying) and an explicit hand-off to create_deposit_order for the exact amount to send. It also encodes a routing rule — offer a native coin only when it appears in supportedSources. No explicit 'when not to use' exclusion is stated, so it falls just short of 5.

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