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

Annotations declare openWorldHint=true and destructiveHint=false, but the description adds substantial context: the call is free and charges nothing, card details must never be passed to a tool, behavior differs with and without a key (guest_checkout creates the account on payment), and paid-plan links are prorated switch confirmations. That is a rich behavioral profile beyond what the annotations state.

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 is front-loaded in the first sentence and every sentence carries operational instruction rather than filler. However, it is a dense single block with long run-on clauses and some repetition (the Stripe/Geocode AI branding is restated), so readability suffers slightly.

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 two-parameter tool with no output schema, the description covers everything an agent needs: what the return value is (a url), how to hand it over, what to tell the human (plan and price), the no-key guest flow, and the follow-up call to verify payment. Nothing essential is missing.

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 both parameters are already documented. The description still adds agent-facing meaning: monthly is the default and yearly: true bills ten months' price once a year, plus the prorated-switch context for existing paid plans. Modest but genuine value over 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 and resource — creates a link a human opens to buy a plan (pro or business) via a Stripe checkout page. It clearly separates this from get_pricing (prices/limits) and get_account (payment status), so an agent can tell it apart from all siblings without opening a 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?

Explicit conditions and exclusions: 'only call it when the human asked to buy or upgrade', 'Never open or pay it yourself', 'Give the url to the human as is'. It also routes to alternatives and follow-ups — get_pricing for prices, get_account to check when it is paid.

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