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

Goes well beyond the annotations: it discloses that the tool itself charges nothing, that the default (no confirm) is a side-effect-free price preview, and that the amount is validated against the returned price. This is exactly the kind of dry-run / safety context annotations alone (readOnlyHint=false, destructiveHint=true) cannot convey.

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 core action and price, then the confirm semantics, then the exclusion. Dense but nearly every clause carries operational weight; the parenthetical pricing could arguably be trimmed for an agent audience.

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 mutation tool with no output schema, it covers the commit/preview distinction, pricing, validation rule, and account-type exclusion. No output schema exists, so return-value explanation is not required, and the description says it produces a Checkout link.

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%, so baseline is 3, but the description adds real cross-parameter meaning: confirm gates execution, and amount must match the price the preview returned. It also clarifies offer is an email-provided founder code, a nuance the schema only partially captures.

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 ('starts an upgrade to Decknote Pro') and the exact mechanism (creating a Stripe Checkout link). It is clearly distinguishable from billing/account siblings like open_billing_portal or update_account because it describes the upgrade-purchase flow itself.

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 explicit call protocol: without confirm:true it is a preview, with confirm:true it commits, and amount must equal the quoted price. It also states a clear exclusion – Shopify-billed accounts upgrade elsewhere. It stops short of naming a specific alternative sibling tool to use in that case.

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