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

Annotations indicate readOnlyHint=false, so the mutation is already known. The description adds behavioral detail beyond annotations: it explains the removal capability via remove=true, and the timing effect on the discounted total before checkout. It does not contradict the annotations and provides useful operational context about how the cart total is affected.

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 description is three concise sentences, front-loaded with the main purpose, then usage context, and a parameter-specific note. Each sentence adds essential information without redundancy or filler, making it easy to parse and act upon.

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 tool with 3 simple parameters, no output schema, and minimal annotations, the description covers the core aspects: what it does, when to use it, and how removal works. It is well-integrated with sibling context via the checkout ordering hint. The only minor gap is not mentioning potential error handling or invalid codes, but the description is complete enough for straightforward invocation.

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?

The input schema covers all three parameters with descriptions, so the baseline is 3. The description restates the remove parameter ('Set remove=true to take a code off') but does not add substantial meaning beyond the schema. No additional parameter details are needed due to high schema coverage.

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 clearly states the tool's function with a specific verb and resource: 'Apply (or remove) a promo / discount code on the Bookeasy cart.' It explicitly distinguishes from sibling tools by mentioning the correct timing relative to bk_cart_checkout and the removal option, so the purpose is unambiguous and differentiates among cart-related operations.

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?

The description provides clear usage context: 'Use when the user gives a promo code; call before bk_cart_checkout so the discounted total shows.' This gives an explicit when-to-use and an ordering guideline. It does not explicitly state when not to use or name alternatives, but the context is sufficient for an agent to select this tool appropriately among siblings.

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