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

With annotations only covering safety (readOnly=false, destructive=false, openWorld=true), the description goes well beyond them: it explains that the customer is NOT booked yet, describes the auto-fill window timing vs. manual staff placement, notes the default per-call confirmation switch, warns that this reaches other people, and names the API-key access prerequisite.

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, but the opening two sentences ('Add a customer to the waitlist of a full class' / 'Puts one customer on the waitlist of a class that is full') restate the same fact, and the confirmation instruction appears twice ('you confirm each call' vs. 'confirm with the user before each call'), which is redundant and slightly ambiguous.

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 mutation tool with no output schema, it covers purpose, operational behavior, confirmation policy, and auth prerequisites, which is nearly everything the agent needs. It stops short of noting error/edge behavior (e.g., customer already on the list), keeping it just under fully complete.

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%, so class_id, customer_id, and payment_option_id are already fully documented with defaults and sourcing hints. The description only adds 'the payment option you choose,' a marginal reinforcement of the optional payment_option_id, so the baseline 3 applies.

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 with scope: 'Add a customer to the waitlist of a full class.' It is clearly distinguishable from every mariana-tek sibling (book_reservation, add_customer_note, cancel_reservation, etc.), none of which touch the waitlist.

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 the selecting condition implicitly ('a class that is full'), which helps the agent know when this applies, but it never names the alternative operation to use when a class is NOT full (e.g., book_reservation). Usage is inferable but not spelled out against a sibling.

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