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

Annotations already flag destructiveHint=true and idempotentHint=true, so the description's real added value is the warning that setting status to donotcontact or deleted stops mail, plus the partial-update semantics. This is meaningful behavioral context beyond the annotations, though return shape and permission needs are not addressed.

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?

Front-loaded with 'WRITE' and tight, no wasted sentences. The endpoint POST /contacts/{contactId} is mildly redundant but grounds the operation; overall efficient.

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 15-parameter mutation tool with annotations covering safety and no output schema, the description covers the key gotcha (donotcontact/deleted suppression) and partial-send behavior. Minor gaps on return values and full parameter guidance remain but are acceptable given annotation coverage.

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?

With only 33% schema description coverage across 15 params, the description compensates partially by explaining partial-update behavior and the consequence of the status enum values. It does not add meaning for the other 10+ undocumented fields, but the schema does carry types and constraints.

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+resource (change fields of one contact) and clarifies it is a WRITE operation. Clearly distinguishable from icontact_create_contact and the get/list siblings.

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 'only the fields you pass are sent' note implies partial-update usage, but there is no explicit when-to-use-vs-alternatives guidance (e.g., when to use this vs create_contact or set_subscription). Usage is inferred rather than stated.

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