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

With no annotations, the description carries the full behavioral burden, and it discloses only two facts: the operation is scoped to the signed-in partner, and the password must satisfy 'portal rules'. It says nothing about permissions required, whether a duplicate email is rejected or merged, whether the merchant is notified, or whether the call is idempotent — significant gaps for a creation mutation.

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 short sentences with zero filler, and the creation intent plus tenant scope are front-loaded. It is not padded, though it is arguably under-specified rather than genuinely concise.

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 five-parameter mutation with no annotations and no output schema, the description covers only the two required fields and omits optional phone/country/intentId, side effects, and error behavior. It is minimally adequate but leaves the agent to rely entirely on the schema for anything beyond the happy path.

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 schema already documents all five parameters, establishing a baseline of 3. The description adds only the password-policy constraint, and it ignores the workflow-significant intentId parameter (tied to RecordUserQuestion) that the schema names but does not explain in context.

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 merchant') and scopes it to the signed-in partner, which is enough for an agent to distinguish it from rate/surcharge/label siblings. It does not explicitly name a related alternative such as LookupCustomer or explain the customer-vs-merchant naming, so it stops short of full sibling differentiation.

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 notes prerequisites ('Requires email and a password') but gives no when-to-use guidance, no when-not-to-use, and names no alternative tool. An agent cannot tell from this text whether AddCustomer is the right call versus LookupCustomer or any other customer-related sibling.

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