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

No annotations are provided, so the description carries the full burden. It adds the behavioral detail that the author is the API key's creator, which is valuable. However, it does not disclose other behaviors like whether the note is truly private (invisible to the member), idempotency, permissions required, or what happens on success. This is a gap given no annotations, so a 3.

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?

The description is two concise sentences with no fluff. It front-loads the action and adds the key author behavior in the second sentence. Every word earns its place, so a 5.

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 simple create operation with two well-documented parameters and no output schema, the description is mostly sufficient. It clearly states the purpose and the author attribution. However, it does not mention what the tool returns on success or any potential errors, which could be useful. Given the low complexity, this is a minor gap, so a 4.

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?

The input schema has 100% coverage with descriptions for both parameters, including the crucial clarification that user_id is the profile uuid, not the membership row id. The description adds no additional parameter semantics beyond what the schema already provides, so the baseline of 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?

The description clearly states the verb 'Add' and the resource 'private admin note to a member', which distinguishes it from list_member_notes and other create_* tools. It is specific and not a tautology. It lacks explicit differentiation from siblings, but there is no competing create-note tool, so a 4 is appropriate.

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?

The description implies the use case: when an admin wants to attach a note to a member. However, it does not explicitly state when to use this tool versus alternatives (e.g., when not to use it, or what other tools might be relevant). Since there is no direct alternative for creating member notes, the guidance is minimal but adequate, so a 3.

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