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

Annotations already cover the safety profile (destructiveHint=false, idempotentHint=true, openWorldHint=true), lowering the bar, and the description adds genuinely new behavior: partial-failure semantics reported as succeeded and failed lists. The 'up to 1000' cap is largely redundant with the array param description, keeping this short of a 5.

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 sentences, no filler, and the operation and its limit are front-loaded before the return description. Every clause carries information.

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?

With no output schema, the description usefully characterizes the response as succeeded/failed lists, and all three required parameters are fully covered by the schema while annotations carry the safety and idempotency profile. Nothing needed to invoke the tool 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 description coverage is 100%, so profile_id, phone_number_id and users are all documented in structured fields; baseline is 3. The description only restates the 1000-element cap already present in the users schema description and adds no new syntax (e.g., wa_id vs phone number formatting, behavior on unknown numbers).

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 (unblock) and resource (previously blocked phone numbers) with scope (up to 1000) and target context (on a WhatsApp phone number). The polarity is unambiguous against the sibling whatsapp_users_block and the blocked-users listing tools, so an agent can select it without opening the schema.

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 only implied by the specific verb: the description never states when to reach for this versus whatsapp_blocked_users_list or whatsapp_blocked_user_status (e.g., to first inspect who is blocked), nor any prerequisites. Adequate for an obvious inverse operation, but no explicit routing guidance.

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