Pay: offers add code

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

Annotations already cover safety (readOnlyHint=false, destructiveHint=false, openWorldHint=false). The description adds genuinely non-derived behavior: the code is returned on success, and codes cannot be individually removed, only cascade-deleted with the offer. It stops short of describing error cases or whether adding a duplicate slug overwrites.

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?

Three tight sentences with no filler: purpose first, mode semantics second, lifecycle constraint last. Every sentence conveys information an agent would otherwise have to guess.

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?

No output schema exists, and the description usefully states the return ('the new code'), so return-value ambiguity is addressed. Combined with the lifecycle note and annotation-covered safety profile, the definition is nearly complete; only edge-case behavior on duplicate or invalid codes is unaddressed.

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 all three parameters are already documented, including the omit-for-shared rule on owner_user_id. The description restates that mode distinction but adds no new syntax, format, or constraint detail beyond what the schema carries, 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?

States a specific verb and resource ('Add a promo/referral code to an offer') and immediately spells out the two creation modes: shared promo code vs. personal referral code tied to an owner user id. An agent can distinguish this from pay_offers_codes and pay_offers_user_code by the shared/personal framing alone.

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?

Gives clear when-to-use context via the shared-vs-personal branching rule, and explicitly states the negative case: there is no removal tool, so codes only disappear when the offer is deleted with pay_offers_delete. It does not, however, explicitly contrast itself with the sibling pay_offers_user_code, which also deals with user codes.

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