Create a coupon

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

Goes well beyond the annotations: validation happens before the coupon exists (duplicate code, unknown discount type, impossible date all refused), the return shape is described, and the non-idempotency declared in annotations is explained concretely — sequential retries are refused but overlapping/parallel retries are NOT guarded against, a real duplicate-creation risk. Slightly short of 5 because it doesn't say what a refusal looks like to the caller (error vs. empty result).

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 action and its required inputs, then validation, return, retry caveat, and routing. Every sentence carries distinct information, though the closing auth/ecosystem requirements are a touch terse-compressed for the density of the preceding sentences.

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 4-parameter mutation with no output schema, everything an agent needs is present: required inputs, validation refusals, return values, retry/duplicate hazard, permission requirement, and the boundary against sibling tools.

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 coverage is 100%, so the schema already carries the parameter semantics and a 3 is the baseline. The description adds validation meaning on top — an unknown discount type or impossible date is refused, and the code comes back as WooCommerce stores it (lower-cased) — which is not derivable from the schema alone.

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 ('create a published coupon') plus the shape of what gets created (new unused code, amount, discount type, optional expiry). It also names the sibling it is not — wp_wc_list_coupons — so an agent can route between create and list without opening either schema.

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?

Explicit about when to use it and, crucially, when not to: listing goes to wp_wc_list_coupons and 'changing or deleting one is done in WooCommerce' tells the agent no update/delete coupon tool exists. Also names the precondition (manage_woocommerce, WooCommerce required).

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