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

Annotations only supply destructiveHint=true and a title, so the description carries most of the burden. It adds meaningful context the annotations don't: the note is internal-only, and the call can also mutate status, priority, assignee, due date and tags — a non-obvious side effect that helps explain the destructive hint. It doesn't explain reasons for the destructive classification or reversibility.

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 tight sentences, with the core purpose front-loaded before the side effects. The trailing REST endpoint reference is marginally useful context but not strictly necessary for an agent selecting the tool.

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 12-parameter mutation tool with a nested custom_fields object, the schema covers parameter detail comprehensively and there is no output schema to explain. The description supplies purpose and side effects; it could note that mutating options are best avoided when merely annotating, but overall it is complete enough to call correctly.

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 12 parameters thoroughly (including the alert enum pattern and custom_fields conventions). The description's mention of alerting/status/priority/assignee/due date/tags merely summarizes existing schema fields without adding new syntax or meaning; baseline 3 is appropriate.

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+resource ('Add an internal note') and clarifies scope with 'never sent to the contact', which effectively distinguishes it from the sibling happyfox_add_staff_reply. It stops short of naming that sibling explicitly, so differentiation is implicit rather than explicit.

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 conveys that this is an internal-facing note with optional side effects, which implies when you'd use it (staff-only context) versus a customer reply. However, it never states prerequisites or explicitly names the alternative tool, leaving usage to inference.

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