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

Annotations already declare this is a non-read-only, non-destructive, non-idempotent mutation. The description adds real behavioral context beyond that: existing bookings retain the rules they were booked under, and some values require a plan and a connected Stripe account. It does not say whether the change is immediate or reversible for future bookings, or what the call returns, so it earns credit without being exhaustive.

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-loaded with the purpose, then split into labelled payment and cancellation blocks, so a scanning agent finds a field quickly. It is dense but every clause maps to a parameter or a real constraint; the one cost is that it reads as a long single paragraph rather than a list.

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 12-parameter, zero-required partial-update tool with no output schema, the description covers the field meanings, the plan/Stripe precondition, and the fact that it only mutates what the owner specifies while prior bookings keep their terms. Adequacy is good; it stops short of noting value bounds or the effect on in-flight/unconfirmed bookings.

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?

With only 8% schema description coverage across 12 parameters, the description carries most of the semantic load and largely does: payment's three modes and their prerequisites, deposit as percent OR dollars, tips_enabled, and the meaning of each cancellation field (cutoff, refund window, refund percents, reschedules including "unlimited", policy_note shown to clients). It omits the numeric ranges and the string cap, which the schema encodes but does not explain.

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 description states a specific verb and resource: it sets how clients pay at booking plus the owner's cancellation rules, and it names the two domains and the fields under each. An agent can tell this is a two-section settings writer rather than a booking-creating or scheduling tool, though it never explicitly contrasts itself with siblings like update_calendar_settings or save_calendar_service.

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 gives a genuine usage rule for an all-optional update tool ("Only change what the owner asks") and routes the agent to the dependency sibling: deposit/full require the Manage plan and connect_stripe_for_payments. It does not state when to prefer this over other settings tools, but the conditional prerequisite is explicit and actionable.

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