Pay: plans update

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

Annotations already declare destructiveHint=true and readOnlyHint=false, and the description adds real substance on top: omitted fields keep current values, active/inactive controls plan-picker visibility, and changing amount/currency/interval repoints the plan to a new Stripe price for new sign-ups while existing subscriptions keep the old price. It does not say whether the change is reversible or what the response returns, but for an update tool the mutation consequences are well disclosed.

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 opening two clauses are near-duplicates — 'any --flag overrides; unset = keep' and 'omitted fields keep their current values' say the same thing — which is wasted space in an otherwise dense paragraph. The destructive warning is correctly placed at the end where it is likely to be read.

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 an 18-parameter destructive mutation with no output schema, the description covers the update-vs-create semantics, the picker visibility effect, the Stripe price side effect, and the delete alternative. Nothing an agent needs before calling it 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 description coverage is 100% across 18 params, so the baseline is 3 and each field is already documented. The description still adds a cross-cutting rule the schema only states per-field ('any --flag overrides; unset = keep'), clarifying the patch semantics for all 18 parameters at once.

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 ('Update a subscription plan') and immediately scopes it to the update semantics (any --flag overrides; unset = keep), which cleanly separates it from pay_plans_create and pay_plans_delete in the sibling list. The Stripe-price side effect is also named, so the agent knows this is not a plain field patch.

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?

Explicitly routes the agent away from a sibling: 'Prefer inactive over `pay_plans_delete`.' It also states a precondition for invoking it at all ('check with the user before running it'), so both when-to-use and when-to-prefer-an-alternative are covered.

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