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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false and openWorldHint=false, so the safety profile is covered. The description usefully reinforces the duplicate risk implied by non-idempotency, but never says what happens if a duplicate is still submitted (error vs. silent duplicate record) or whether the call is reversible.

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 dedup precondition is front-loaded right after the purpose statement. Nothing here is redundant with the title.

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 14-parameter mutation with 21% schema coverage and no output schema, the description says nothing about which fields populate what, what the response contains (e.g. a new customer ID usable downstream), or duplicate handling. Adequate for the trigger, insufficient for correct invocation.

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 21% across 14 parameters, yet the description mentions no field semantics at all — not that only `name` is required, not what `address_form` (sie/du), `buyer_reference` or `is_business` control. With low coverage the description should compensate and does not.

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?

A specific German verb+resource ("Neuen Kunden in der Kartei anlegen") that plainly distinguishes this from read-side siblings like get_customer and list_customers. It does not, however, draw any line against sibling write tools such as update_document or create_document.

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 states the precondition for use: check with list_customers first for an existing customer. This names both the alternative tool and the condition that selects it, which is exactly the when/when-not guidance an agent needs.

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