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

The annotations already declare idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is partly covered. The description adds useful behavioral scope by stating that the coupon's discount cannot be changed, but it does not explain edge cases such as lowering max_redemptions below the number of existing redemptions or setting expires_at in the past.

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 description is two sentences and front-loads the core action. Every phrase contributes to scope or constraint, with no redundant restatement of the title or schema.

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 non-destructive, idempotent update tool with no output schema, the description gives enough context to call it correctly: which fields change and which cannot. It is missing some edge-case behavior and does not discuss permissions or validation, but those are secondary for this tool's complexity.

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 low overall at 33%, and the description only addresses max_redemptions and expires_at, largely echoing the nested schema descriptions. It does not explain the id parameter or the analytics context parameter, though the context parameter is well described in the schema itself. The description adds the useful constraint that only limits are mutable, but it does not fully compensate for the coverage gap.

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 uses a specific verb and resource: it changes a coupon code's limits. It names the two mutable fields, max_redemptions and expires_at, and explicitly says the discount amount cannot change, which distinguishes this from a broader coupon edit. An agent can understand the tool's purpose without opening the 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?

The description implies this is for modifying an existing coupon's redemption cap or expiry, but it does not state when to use this instead of create_coupon, discontinue_coupon, or any other coupon operation. The implied context is clear enough, but explicit alternatives and exclusions are absent.

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