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

Annotations only cover the write/open-world/safe profile; the description adds hard behavioral facts the annotations do not: the 3-per-course-per-month limit, non-deletability (irreversibility), the custom-price range bound, Udemy-set durations, and the per-call confirmation default. This is materially beyond what structured fields convey, with no contradiction.

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 core action, but the monthly limit is stated twice ('within Udemy's monthly limit per course' and 'three new coupons per course per calendar month'), and the confirmation policy is split across two similar sentences ('By default you confirm each call' / 'confirm with the user before each call').

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 no output schema, the description covers return values (code and link), the key constraints (quota, non-deletability, price range), and the auth/confirmation requirements. It is nearly complete; only an explicit routing note to list_coupons or sibling create tools is missing.

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 baseline is 3, but the description adds meaning not in the schema: that each coupon type has a Udemy-set duration and that custom_price must fall inside Udemy's offered range. It partly overlaps with schema text (generated code default), keeping it from a 5.

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+resource ('Creates one coupon for a course') and its scope (Udemy's per-course monthly limit), plus the return ('code and link'). An agent can distinguish it from udemy_list_coupons and other vendors' coupon tools without opening a 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?

It gives operating constraints (three per course per month, cannot delete afterwards, custom price within offered range) and a confirmation requirement, which implies when it is appropriate. However, it never frames when to reach for this tool versus an alternative, so usage is only implied rather than explicit.

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