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

The annotations already declare destructiveHint=true, readOnlyHint=false, idempotentHint=false, and openWorldHint=true, so the safety profile is covered. The description adds useful context beyond the annotations: it mandates explicit user confirmation and explains that the tool uses local WordPress authentication with no WooCommerce REST API keys required. It does not describe the return value or error behavior, which keeps it from a 5.

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 definition is three short sentences and front-loads the core action before the confirmation requirement and authentication note. Every sentence is relevant, though the reference to mirroring the woocommerce-mcp-server method is more contextual than necessary for invocation.

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 destructive mutation tool with no output schema, the description covers the confirmation guardrail and authentication model well. However, it does not explain which coupon fields couponData accepts or whether the update is partial or full, leaving a meaningful gap for an open-ended nested object.

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 the schema carries the primary burden of documenting site_id, couponId, couponData, and confirm. The description reinforces the confirm workflow but adds no field-level meaning for couponData, which is an open-ended nested object. A baseline 3 is appropriate because the schema already documents the parameters.

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: 'Updates a WooCommerce coupon.' That is clear enough to distinguish it from create, get, and delete coupon operations, but it does not explicitly name or compare against those siblings, so it falls short of a 5.

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 an important usage prerequisite: ask the user for confirmation before calling with confirm=true. However, it does not say when to choose this tool over alternatives such as wc_create_coupon or wc_delete_coupon, nor does it describe any exclusions or conditions beyond the confirmation requirement.

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