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

Annotations already flag this as a write (destructiveHint=true) and the description reinforces that with the POST /activities endpoint, which does not contradict the annotation. However, it adds nothing about permissions, whether activities are editable/removable after logging, or failure behavior — the annotation bar is lower, but the description contributes only the endpoint detail.

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 short sentences, front-loaded with the action and scope, then the dependency, then the endpoint. No filler or repetition.

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 5-parameter write tool with full schema coverage and no output schema, the description covers purpose, prerequisite, and transport. The remaining gap is the mildly surprising destructiveHint=true on an append-style operation, which the description never acknowledges or explains.

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 all five parameters (including parent_type enum and activity_date default) are already documented in the schema; the 3 baseline applies. The description's pointer to copper_list_activity_types for activity_type_id duplicates what the schema field description already says, adding no new semantics.

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?

Specific verb+resource ("Log a user activity ... on a record") with concrete examples (note or call) and the underlying REST verb/endpoint (POST /activities). No sibling tool performs the same action, so an agent can distinguish it from copper_create_* and copper_list_activities without opening the schema.

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 routes the agent to the prerequisite tool ("Get the activity_type_id from copper_list_activity_types"), which is genuine usage guidance. It does not state when-not to use it, nor when to prefer it over copper_create_task for logging a follow-up, so it stops short of a 5.

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