whatsapp_set_newsletter_subscription

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

Annotations already declare idempotentHint=true, destructiveHint=false, and openWorldHint=true, so safety and repeatability are covered. The description adds genuine context beyond that: what following actually does to the account ('adds its updates to this account'), the privacy consequence ('the channel owner only sees the follower count'), and the return shape ('a success confirmation').

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 sentences, front-loaded with the operation, then the behavioral consequence, then the return value. No filler and nothing an agent must skip past to find the action.

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, idempotent, non-destructive operation with no output schema, the description covers the action, the effect, the visibility implication, and the return value. It omits auth/session prerequisites, but nothing else needed to call it correctly is missing.

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 coverage is 100% — both the JID and the boolean subscribed flag are already documented in the schema. The description reinforces that action happens 'by JID' and that subscribing adds updates to the account, but adds no format, validation, or edge-case detail beyond the schema. Baseline 3 is correct.

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 pair (follow/unfollow) and resource (channel/newsletter by JID), which is enough to separate it from siblings like whatsapp_mute_newsletter or whatsapp_get_newsletter. The only weakness is terminology drift: the tool and schema say newsletter, the description says 'channel', which an agent must map back to the sibling naming.

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?

Usage is implied by 'Follow or unfollow a channel by JID' — the agent can infer this is the subscribe/unsubscribe action. However, no explicit when-to-use guidance or alternatives are named, e.g. it never says to use whatsapp_mute_newsletter instead when the user only wants to silence a channel without following it.

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