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

Annotations only carry the generic safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=false). The description adds genuinely non-obvious behavioral context: the discount is charged against the operator's payout rather than the platform commission, and it discloses the return ("the stored discount"). It still omits auth/validation requirements, keeping it short of 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?

Two compact clauses with the action and the key financial constraint front-loaded, plus a brief return note. No filler; every sentence earns its place.

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 15-parameter mutation tool with no output schema, the description covers the risky/ambiguous part an agent most needs (who bears the cost) and states the return shape. It lacks prerequisite/auth context and any reference to the update/delete counterparts, but the schema carries the field-level burden.

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 87%, so the schema already documents nearly all 15 parameters, including the code-vs-pay_in_full trigger rule and currency defaults. The description adds no parameter-level detail beyond an indirect hint about how discount_value financially lands, 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?

States a specific verb and resource ("Create a discount") and adds the crucial business framing that the discount is deducted from the operator's payout, not the platform commission. This is more informative than a bare CRUD restatement, though it never explicitly distinguishes itself from update_discount/delete_discount siblings.

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?

No guidance on when to create a discount versus updating one, no prerequisites (permissions, existing company), and no routing to list_discounts/update_discount. The schema hints at trigger semantics but the description offers no usage context.

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