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

Beyond the annotations (which cover read/write and open-world flags), the description discloses the return behavior, the immediate price-change effect, the variant limitation, the default per-call confirmation flow and how to disable it, the external-visibility warning, and the API key requirement. This is unusually rich behavioral context for a mutation tool.

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?

Front-loads the action and is largely waste-free, but the confirmation guidance spans two overlapping sentences ('By default you confirm each call...' and 'Reaches other people: confirm with the user before each call.') that read as slightly redundant.

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, it covers return behavior, side effects, scope limits, confirmation and auth. The only remaining gap is that partial-update semantics and the 'fields' string format are left entirely to the schema.

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 baseline is 3. The description restates the same field names as the schema and adds no format detail for the 'fields' string (e.g., how to express a visibility value), so it does not go beyond structured data.

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 (Change) and resource (product) plus the exact scope of updatable fields (title, price, description, visibility). An agent can distinguish this from payhip_create_product or payhip_list_products without opening any 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?

Explicitly excludes a class of products (those with variants are not covered) and warns that price changes take effect on new orders immediately, which is real when-to-use context. No named alternative is offered for the excluded variant case, so it stops short of a full routing guide.

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