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

Annotations already declare destructiveHint=true, so safety is signaled structurally. The description adds the scope of mutation (code text and/or max purchase count) and the underlying PUT endpoint, but does not disclose consequences such as existing redemption links breaking when code text changes, or whether unspecified fields are reset by the PUT.

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 tight sentences, front-loaded with the action and mutable fields; the API endpoint reference is compact and earns its place by anchoring the operation. No filler.

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 4-parameter mutation with no output schema, the description covers the actionable scope and the destructive annotation carries the risk profile. The one gap is ambiguity about partial vs. full update semantics ('and/or' versus PUT's typical replace behavior), which could mislead an agent about omitted fields.

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 four parameters are already documented in the schema with the same meanings the description implies. The description's enumeration of mutable fields adds no syntax or format detail beyond the schema, 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 (Update) and resource (an existing offer code on a product), and names the exact mutable fields (code text and/or max purchase count). It is clearly distinguishable from siblings like gumroad_create_offer_code, gumroad_get_offer_code, and gumroad_list_offer_codes.

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 'Update an existing offer code' implies the tool is for modification rather than creation or retrieval, but it never states when to prefer it over create/get, nor any prerequisites such as needing the code to already exist. Usage is implied, not spelled out.

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