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

Annotations already declare readOnly=false, destructive=false, idempotent=false, and openWorld=true, so safety is covered. The description adds genuinely new behavioral context not in the annotations: the cost model ($0.001 per call, nothing if it fails), which affects whether an agent invokes it speculatively. Auth and reversibility are not covered, keeping it from a 5.

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?

Purpose is front-loaded and the illustrative phrases are useful, but the pricing is stated twice ('$0.001' then 'Costs $0.001 per call; nothing if it fails'), which wastes space. The nominal opening phrase is slightly weaker than a direct verb.

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 3-param write tool with no output schema, the description covers purpose, examples, and cost but says nothing about what is returned (note id, timeline entry) or confirmation behavior. Annotations handle the safety profile, so this is adequate but leaves the return contract unstated.

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 coverage is 67%; the id and the object enum carry inline descriptions, but body has only length constraints and no semantics. The description adds no detail on the body content format, so it neither compensates for that gap nor extends any parameter meaning beyond the schema.

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?

Establishes the concrete resource and scope: a note on a contact, company, deal or ticket's timeline. The implied action (adding a note) is clear from the title. It does not distinguish itself from the sibling crm_add_note, which is a near-identical capability, so an agent cannot tell the two apart from the description alone.

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 use-case examples ('what a customer said on the phone, what was agreed') imply when to reach for it. But there is no explicit guidance on when to use this versus crm_add_note or other HubSpot write tools, and no exclusions or prerequisites.

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