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

Annotations already flag destructiveHint=true and readOnlyHint=false, so the safety profile is known; the description usefully qualifies that behavior by declaring partial-update semantics where omitted fields are preserved, which is exactly the kind of nuance annotations cannot express. It still omits auth requirements, error behavior, and whether the response returns the updated record.

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 short sentences, front-loaded with the action and then the two rules that actually change how the call is built. No filler and no repetition of the tool name.

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 9-parameter mutation tool with no output schema, the description covers the two things an agent could plausibly get wrong: full-object overwrite risk and price/currency formatting. A note on what is returned or on failure modes for an invalid product_id would close the remaining gap.

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 coverage is only 44%, so the description should compensate more than it does. It adds real meaning for price (major units as a string, with an example) and reinforces that currency belongs with price, but url, name, brand, image_url, and description remain undocumented beyond self-evident names.

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 ("Edit an existing catalog product"), which cleanly separates it from create_catalog_product, delete_catalog_product, and the campaign/adset siblings. It does not explicitly route to list_catalog_products for reads, but the operation is unambiguous.

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?

"Send only the fields you want to change; omitted fields are left as-is" is a concrete invocation rule that tells the agent to send a sparse patch rather than a full object. No explicit when-not or named-alternative guidance is given, which keeps it out of 5 territory.

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