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

Annotations already declare the tool is not read-only, not destructive, and idempotent. The description adds the important behavior that the notes are 'replaced' (fully overwritten), which is a semantic detail beyond the annotations. However, it does not disclose any potential side effects, such as whether null clears notes or if existing notes are truncated, but this is a minor gap.

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 extremely concise: 'Update Customer Notes' followed by 'Replace the internal notes stored on a customer.' It is front-loaded with the key action and has zero filler. Every word earns its place.

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 tool with only two parameters, 100% schema coverage, and an output schema, the description is sufficient. It explains the core action, and the schema handles parameter details. The only omission is potential edge-case behavior (e.g., passing null to clear notes), but that is implied by 'Replace'. Overall, adequate 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?

The schema covers both parameters with descriptions (id and notes), so baseline is 3. The description's use of 'Replace' adds nuance that the notes parameter is overwritten entirely, providing slight extra meaning beyond the schema. However, it does not explicitly describe parameter semantics beyond that.

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 states a clear verb ('Replace') and resource ('internal notes stored on a customer'), which precisely identifies what the tool does. It differentiates from sibling tools like updateCustomerTags or updateCustomerPhoto by focusing specifically on notes.

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?

No explicit guidance on when to use this tool versus alternatives, but the name and description make it obvious that it is used when updating customer notes. There is no mention of when not to use it or alternative workflows, but the simplicity of the operation makes the usage implicit.

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