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

Annotations already declare idempotentHint=true, destructiveHint=false, and readOnlyHint=false, so the safety profile is covered by structured data. The description adds nothing beyond this - it doesn't explain partial-update semantics (that all fields except 'id' are optional and only supplied fields change), nor what happens on an unknown ID. With a mutation tool touching 13 fields, richer disclosure would be warranted.

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 single sentence has zero waste and is front-loaded, which is good. But it is undersized relative to the tool's complexity (13 parameters, no output schema), so 'appropriately sized' is only partially met.

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 13 parameters and no output schema, the description omits essential context: whether this is a partial or full update, what the response contains, and how errors (e.g., invalid coupon ID) surface. Annotations cover only the safety profile, leaving meaningful gaps.

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 every parameter is already documented in the input schema, including the ISO 8601 expiry format and the enum for discount_type. The description provides no additional parameter meaning, so the baseline of 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?

The description names a specific verb ('Update') and resource ('WooCommerce coupon'), which is immediately understandable. However, it does nothing to differentiate this tool from its close siblings woo_create_coupon, woo_get_coupon, and woo_list_coupons beyond the name itself.

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?

There is no guidance on when to use this tool versus woo_create_coupon or woo_get_coupon, no mention of prerequisites (e.g., the coupon must already exist), and no exclusions. The agent must infer everything from the name.

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