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

Annotations provide only destructiveHint=true and a title, so the description carries most of the burden. It hints that the note becomes visible on the contact's timeline and cites the raw endpoint 'POST /v1/notes', but says nothing about permissions, whether the note is editable/deletable, rate limits, or what the response looks like for a mutation tool.

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 short sentences with the purpose front-loaded; the API endpoint reference is developer-facing filler but costs little space. Nothing is buried or padded.

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 4-parameter append tool with no output schema, the description covers the core action adequately. However, with annotations limited to destructiveHint, it leaves unanswered how the note interacts with the contact record and when to choose this over sibling timeline tools.

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% (body, isHtml, subject, personId all documented), so the baseline is 3. The description adds no format, length, or HTML-escaping guidance beyond what the schema already states.

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 and resource ('Add a note to a contact's timeline'), which is distinct from the many creation/list siblings like fub_create_task and fub_log_call. It does not explicitly name an alternative, but the resource is unambiguous enough that an agent can tell what it does 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?

There is no when-to-use guidance, no prerequisites, and no mention of alternatives such as fub_log_call or fub_send_lead_event for other timeline entries. Usage is only implied by the tool name and the word 'timeline'.

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