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

Annotations already declare openWorldHint=true, idempotentHint=false and destructiveHint=false; the description corroborates the write side effect ('writes to the user's books') and adds genuinely new context about reversibility (records can be archived or deleted later). It omits what happens on duplicate email/name, validation failures, and whether the created record is immediately usable elsewhere, which matters for an 11-param write 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?

Three short sentences, front-loaded with the action and with the required-field constraint early. The trailing 'POST /customers' is the only questionable sentence, though it does anchor the tool to a concrete API shape.

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?

No output schema exists, so the description carries the burden of describing the return value, and it says nothing about what a successful create returns (e.g. the new customer id) or how the agent should reference the customer afterwards. For a mutation tool with 11 mostly-undocumented parameters, missing duplicate/validation behavior is a real 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 description coverage is only 27%, so the description needs to compensate, but it only restates the required-field fact ('Only display_name is required') which the schema's required array already conveys. Of the ten optional fields (tax_no, associate_company, billing_address, first/last name, etc.) none are explained, so an agent gets no help choosing between display_name and first_name/last_name or knowing how billing_address differs from address.

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 new customer contact in Jurnal'), which is unambiguous against read siblings like jurnal_get_customer and jurnal_list_customers. It never explicitly contrasts with jurnal_create_vendor, the closest sibling, but the resource noun does the disambiguation work.

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?

Usage is implied by the verb and by 'Only display_name is required', so an agent knows the minimum viable call. There is no guidance on when to create a new customer versus pick an existing one, no duplicate-handling advice, and no mention of the vendor sibling.

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