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

Annotations already declare write, non-idempotent, non-destructive, and open-world behavior, so the bar is lower. The description still adds real value beyond them by disclosing who can see the note and that a new note id is returned, though it says nothing about permissions or failure behavior.

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 fragments with the operation type front-loaded first and the endpoint last; every element (verb, scope, return value, route) carries information an agent would otherwise have to guess at.

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 two-parameter mutation with no output schema, the description covers the essentials: what is written, who sees it, and what comes back. Only edge behavior (invalid lead id, oversize note handling) is left unaddressed, and the schema's maxLength covers part of that.

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%, with both lead_id and note documented including length bounds, so the description does not need to compensate. It adds no syntax, formatting, or ID-sourcing detail beyond the schema, making the baseline 3 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 and resource ('adds a note to a lead'), scopes the effect ('visible to the account's agents'), and names the return value and underlying endpoint. This is clearly distinguishable from idx_list_lead_notes and idx_update_lead without opening any 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?

The 'WRITE:' prefix and the visibility note imply this is for appending agent-visible notes rather than reading them (idx_list_lead_notes) or editing the lead (idx_update_lead), but no alternative or when-not-to-use condition is stated explicitly. Usage must be inferred from the verb.

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