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

With annotations only declaring readOnlyHint=false, openWorldHint=true, idempotentHint=false and destructiveHint=false, the description carries the real behavioral burden and does so: it discloses the return value (secure Stripe checkout URL plus plan terms), the side-effect boundary (does not charge or activate), pricing, and the first-time-subscriber discount. This is substantially more than the annotations provide.

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 action, the plan menu, and the 'does not charge' caveat are front-loaded, and every sentence carries usable information. The pricing enumeration is somewhat dense for a single description, but it directly supports plan selection rather than padding.

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 single-parameter, single-purpose tool with no output schema, the description covers prerequisites, return shape, and the non-charging guarantee, leaving nothing an agent needs to call it correctly unstated.

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% with an enum, so the baseline is 3, but the description earns extra credit by explaining each enum value's price and duration (day_pass $3/24h, plus_monthly $10/mo, plus_yearly $100/yr) and flagging day_pass as the popular on-course choice. That is decision-relevant meaning the schema's terse 'The plan the golfer chose.' does not provide.

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 opening sentence names a specific verb and resource ('Create a GolfCore Premium checkout link') and scopes it to the signed-in golfer, which is entirely distinct from the read-only siblings (ask_caddie, distance_to_flag, search). An agent can identify the tool's function without opening the 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?

It states the prerequisite explicitly ('Ask the golfer which plan they want before calling') and clarifies the tool's boundary ('this tool does not charge them or activate Premium'). No alternative subscription tool exists among the siblings, so no when-not guidance is needed, but the agent still has to infer that this is the only path to Premium.

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