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

Annotations already declare destructiveHint=true, idempotentHint=true and readOnlyHint=false, so the safety profile is carried structurally. The description adds one non-obvious behavioral fact: unspecified fields are preserved (PATCH-like, not replace). However, it does not explain why the tool is flagged destructive, nor what happens to dependent links/visibility when fields change — a notable gap 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?

A single efficient sentence with the partial-update constraint front-loaded. It is not padded, though its brevity borders on under-specification rather than tightness.

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 13-parameter destructive mutation with no output schema, the description omits enum semantics, the effect of visibility changes, error behavior for an invalid contactId, and what the response returns. Given the low schema coverage, far more disclosure was needed.

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 only 15% across 13 parameters, so the description must compensate and it does not. It never mentions the required contactId, the kind or visibility enums, or the meaning of visibility values ('private' vs 'ecosystem' vs 'public'), leaving most parameters undocumented anywhere.

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?

The description states a specific verb and resource ('Update fields of a contact'), which is unambiguous on its own. It does not differentiate from adjacent tools in the same family such as vitalli_update_organization or vitalli_link_contact_to_org, but the operation itself is clear.

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 statement of when to use this versus vitalli_create_contact, vitalli_get_contact, or vitalli_delete_contact, and no prerequisites. The parenthetical implies partial-update semantics but does not tell the agent under what circumstances to choose this tool.

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