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

Goes well beyond the annotations: despite readOnlyHint=false and idempotentHint=false, it explains that the call creates a checkout link and changes nothing else on the account, that a 30% first-month offer may be attached, and that get_setup_status will reflect the new plan afterward. That is exactly the side-effect and state-transition context the annotations 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 behavior and is mostly dense with useful constraints, but the trailing remark about get_setup_status returning next_step.say is tangential to this tool and the plan/interval defaults duplicate the schema. Slightly longer than necessary, though no sentence is outright waste.

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?

Strong coverage of preconditions, side effects, and sequence for a mutating setup tool with no output schema. The gap is return shape: it never says where the link appears (field name) or whether links expire or are reusable, which matters since there is no output schema to fall back on.

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 enum descriptions for both parameters, which already state the practitioner/monthly defaults. The description repeats those defaults but adds no new semantics such as eligibility differences per plan or interval consequences beyond the trial. Baseline 3 is appropriate when the schema does the heavy lifting.

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 precise verb and resource: returns a Stripe checkout link for a free 14-day trial. It also scopes the audience (accounts with no plan, Practitioner and above) and names the related siblings (get_setup_status, get_desktop_app), so an agent can tell it apart from the rest of the setup family.

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 when-to-use and when-not-to-use: only accounts with no plan yet, only Practitioner and above, and Novice has no MCP or API. It even supplies the ordered setup sequence (get_setup_status → start_trial → get_desktop_app) so the agent knows where this call sits relative to alternatives.

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