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

Annotations already state readOnlyHint=false, destructiveHint=false, and idempotentHint=false, so the safety profile is known. The description adds the partial-update behavior (only changed channels are passed), which is valuable, but says nothing about whose preferences are modified, whether a read-back is returned, or that omitting a field preserves its current value explicitly.

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?

Two short sentences, front-loaded, with no filler. It is slightly too terse in the first sentence, where "update channels" costs clarity that a few more words would have bought.

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 small mutation tool with no output schema, this is minimally adequate: the patch semantics are the essential fact and they are present. Missing are the read-modify-write pairing with get_notification_preferences and confirmation of what the call returns or affects.

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 0% schema description coverage and four boolean params, the description does carry real weight: the patch instruction implies unspecified channels are left untouched, which is key semantics the schema cannot convey. However, it never explains the four channels themselves or that whatsapp_marketing is a narrower WhatsApp case, so names alone must carry that meaning.

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?

"Turn update channels on or off" gives a verb and an object, but the object is phrased oddly ("update channels" rather than notification channels/preferences), so the resource is only pinned down by the tool name and title. An agent can guess it toggles notification delivery channels, but the sentence alone is vague about what is being changed.

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?

"Only pass the ones they asked to change" is a partial-usage instruction, which is useful, but there is no when-to-use framing and no mention of the obvious sibling get_notification_preferences for reading current settings. Nothing tells the agent when this tool is the right choice versus the read counterpart.

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