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

Annotations already declare readOnlyHint=false and destructiveHint=false, and the description reinforces this with "an additive note, nothing is overwritten," which is a useful non-destructive guarantee rather than a restatement. It also discloses the default visibility behavior (internal only) and the underlying endpoint, though it says nothing about permissions or what is returned on success.

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 sentences, zero filler: the operation type, target scope, non-destructive nature, visibility default, and endpoint are all front-loaded. Every clause carries information an agent needs before calling.

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 4-parameter, non-destructive write with annotations and no output schema, the description covers scope, default behavior, and endpoint. The remaining gap is what a successful call returns (comment id, timestamps), which an agent may want for follow-up calls.

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 75%, so the baseline is 3; the description earns an extra point by adding policy beyond the schema for visible_for_contact ("only make it visible when the user explicitly asks") rather than just repeating the default. The enumerated reference targets also clarify reference_type semantics, though the 5000-character text limit is left entirely to the schema.

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?

The description leads with a specific verb+resource pair ("add an internal comment") and enumerates exactly which entities can be commented on (order, order item, contact, category, variation), matching the reference_type enum. The "WRITE" prefix immediately separates it from the read-oriented siblings like plentymarkets_list_comments and plentymarkets_get_order.

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?

It gives explicit conditional guidance for the one judgment call an agent must make: keep the comment internal by default and set visibility only when the user explicitly asks. It does not name an alternative tool (e.g., use plentymarkets_list_comments to read existing notes), so it falls just short of the full when/when-not/alternatives bar.

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