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

Annotations already declare readOnlyHint=true, and the description adds valuable behavioral detail: each entry contains number, optional saved name, and country, and that WhatsApp provides no block date. This goes beyond the structured fields and helps set agent expectations about the data shape and limitations.

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 sentences with no wasted words. The main action is front-loaded, the return entry details are compactly listed, and the date limitation is stated as a meaningful constraint rather than filler.

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 simple one-parameter read operation with a readOnly annotation and an output schema present, the description fully equips an agent to invoke the tool correctly. It explains what the response will contain and what it will not contain, leaving no critical gap.

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 schema description coverage at 100%, the schema already fully documents account_id as 'the account whose blocklist to read, as returned by wa_list_accounts'. The description adds no parameter-specific meaning, so the baseline of 3 is appropriate.

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 states a specific verb ('List'), a clear resource ('every contact one of your accounts has blocked'), and the account-scoping. It is immediately distinguishable from sibling tools like wa_list_contacts and wa_list_accounts by the blocked-contact focus.

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 description clearly establishes the context: reading the blocklist for a specific account, and the account_id parameter references wa_list_accounts. It does not explicitly name alternatives or when-not-to-use it, but the intended use is unambiguous and the sibling set makes the distinction evident.

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