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

Annotations already declare readOnlyHint=false and idempotentHint=false, but the description earns credit by spelling out the concrete consequence: "calling it twice creates two coupons." It also warns the coupon is immediately redeemable in the live account, which is real operational context an agent must consider. It stops short of covering permissions or what the response returns.

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?

Two dense sentences front-loaded with the WRITE prefix and the endpoint at the tail. Every clause carries information: mutation type, immediacy, cardinality of discount vs. codes, optional constraints, and idempotency warning.

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 the write semantics, live-effect risk, idempotency trap and endpoint, which is what an agent most needs before calling. The only real gap is not hinting at what a successful creation returns (e.g., a coupon id) for follow-up calls.

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 already documents name, codes, expires, form_id, currency, available, discount_type and discount_value in detail. The description's summary sentence ("one discount (fixed amount or percent) and one or more codes; optionally limited to…") restates the schema at a high level without adding format or validation nuance, so baseline 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?

Opens with an explicit "WRITE: create a discount coupon" verb+resource pair and names the target system (live GivingFuel account), which cleanly separates it from the read/delete coupon siblings. The scope detail (one discount, one or more codes) further pins down exactly what is created.

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?

The phrase "it can be redeemed by donors right away" tells the agent this is a live, donor-facing effect, and the optional constraints (form, uses, expiry) signal legitimate narrowing. It does not explicitly state when to prefer create vs. reusing an existing coupon via get_coupon/list_coupons, so it falls short of full alternative routing.

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