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

Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=false, and the description adds real value on top: the append-only semantics ('each call adds a new note'), audience visibility (staff only, not sent to the customer), and the underlying endpoint. It does not cover permissions or rate limits, which keeps it from a 5.

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 compact sentences, front-loaded with the 'WRITE' signal and the internal-visibility constraint, then the append warning, then the endpoint. Nothing is wasted and nothing essential is buried.

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 and fully documented parameters, the description supplies the mutation type, the repeat-call warning, and the visibility semantics an agent needs before invoking. Only error behavior and any confirmation/return detail are absent, which is minor.

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 all three parameters are already documented, including order_line_id's 'attach to this line item instead of the order' behavior. The description restates the order_line_id routing but adds no syntax or format guidance beyond the schema, so baseline 3 applies.

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 ('add an INTERNAL note ... to an order, or to one line item'), and the 'visible to staff, not sent to the customer' clause removes any ambiguity about note type. It does not explicitly contrast itself with the sibling tools, though none of them create notes, so confusion risk is low.

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 rather than stated: it is clearly the tool for internal, staff-visible notes as opposed to customer-facing communication. The only explicit guidance is 'Each call adds a new note, so do not repeat it', which is a non-idempotency warning rather than a when-to-use vs alternative rule.

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