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

Annotations already declare readOnlyHint=false, idempotentHint=false, and destructiveHint=false, so the safety profile is partially covered. The description adds nothing beyond that, and notably omits any mention of the approval_id governance flow, which is behaviorally significant for a mutation. Thin disclosure for a write operation.

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 short sentence with no waste, and the precondition is front-loaded. It is efficient, though written as a sentence fragment that reads more like a use case than a definition.

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?

An output schema exists, so return values need not be described. But for a mutation tool with an approval_id parameter implying a human-approval workflow, the description leaves that process and prerequisite unexplained, falling short of complete.

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 the schema already documents all three parameters, making 3 the baseline. The description adds light color by naming example values ('a new phone number or email') and referencing the field id, but adds no syntax or format detail 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?

The description frames a scenario ('when one of a contact's details changed') rather than stating what the tool does, so the verb+resource must be inferred from the name/title. It does not differentiate from the sibling contacts.update, which appears to serve a similar role. Adequate but vague.

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 gives a precondition for use ('when a contact's details changed... and you have the field id'), which is implied usage guidance. However, it never mentions alternatives such as contacts.update or contacts.fields.list, nor when not to use it. No explicit routing.

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