Create a discount coupon for a book by providing the book slug, coupon code, discounted price, and start date. Define optional limits like end date and max uses to manage promotions.
Create a new coupon for a book.
| Name | Required | Description | Default |
|---|---|---|---|
| note | No | ||
| slug | Yes | ||
| endDate | No | YYYY-MM-DD | |
| maxUses | No | ||
| startDate | Yes | YYYY-MM-DD | |
| couponCode | Yes | ||
| packageSlug | No | Default 'book' | |
| discountedPrice | Yes |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations at all, the description carries the full burden of behavioral disclosure. It only says "Create a new coupon" and does not mention side effects, duplicate handling, date validation, read/write implications, or what happens when required fields are missing. For a creation tool, this is a significant transparency gap.
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 concise and front-loaded, but it is under-specified. It is a single sentence with no fluff, yet it lacks almost all useful detail an agent needs, so its brevity is not an asset here.
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?
Given 8 parameters, 4 required fields, no output schema, and no annotations, this one-line description is far from complete. It does not state return behavior, required field semantics, date formats, uniqueness constraints, or how coupon creation relates to the book resource.
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 only 38%, so the description must compensate, but it adds no parameter-level meaning. It does not explain couponCode, discountedPrice, startDate, maxUses, slug, note, or how "for a book" maps to packageSlug or slug. The only hint is the word "book," which is too vague.
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 clear verb and resource: "Create a new coupon for a book." It distinguishes this tool from siblings like list_coupons, get_coupon, and update_coupon by signaling creation rather than retrieval or modification.
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?
No guidance is given about when to use this tool versus alternatives, nor any prerequisites or exclusions. An agent must infer from the tool name that this is the creation path, and there is no mention of conditions such as uniqueness of couponCode, required book existence, or relationship to packageSlug.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.