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

Annotations already declare readOnlyHint=false, idempotentHint=false and destructiveHint=true, so the safety profile is covered. The description adds real value beyond them: the note is internal-only (never sent to the customer), it returns the note id, and it hits POST /note. It does not explain the destructiveHint=true side effect or failure behavior.

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 tightly packed sentences, front-loaded with the WRITE signal, then scope, then behavioral clarification, then return and endpoint. No filler.

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, but the description states the return value (note id), and the schema covers all required params and the enum. Only edge cases (record not found, max length enforcement) are unaddressed, which is minor for a simple write tool.

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 three parameters including the enum and the billing_package/user aliases. The description largely restates those same record types, adding only the human-readable mapping (subscription, contact), which is the baseline 3 case.

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 (add a note) and resource, and enumerates exactly which record types it attaches to, which cleanly separates it from chargeover_list_notes and the create_* siblings. The 'WRITE:' prefix and endpoint make the operation unambiguous.

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?

Implied usage is clear (attach an internal note to an existing record), and the parenthetical clarifies the note is team-visible and never customer-facing. However, it names no alternatives and gives no when-not-to-use guidance (e.g., versus chargeover_list_notes or update tools), so routing must be inferred.

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