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

Annotations already declare readOnlyHint=true and destructiveHint=false, so 'a read: nothing is changed' restates structured data. What does add value is the 'Live apps only' scope limit and the note that this is a POST endpoint performing a read, which prevents an agent from assuming a side effect from the HTTP verb. No auth, rate-limit, or empty-queue behavior is described.

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 fragments, result described first, then eligibility, then a clarifying note on the HTTP verb. Every clause carries information; nothing is padded.

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 does at least say the return is a per-number queue count, and annotations cover the safety profile. Minor gaps remain around what an empty queue or an unowned number yields, but the definition is sufficient for correct invocation.

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?

There is a single parameter with 100% schema coverage, including a regex pattern and a 1-20 item range, so the schema carries the load. The description adds nothing about the phone_numbers array beyond 'your voice numbers'. Baseline 3 applies.

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 resource and quantity: 'Number of outbound calls currently queued on each of your voice numbers', plus the underlying endpoint. No sibling tool touches voice queues, so an agent can pick it out immediately 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?

The 'Live apps only' qualifier gives one real eligibility constraint, and the implied context (check queue depth on your own numbers) is inferable. But there is no explicit when-to-use, no when-not-to-use, and no named alternative.

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