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

With no annotations, the description carries the full burden and does disclose a genuinely non-obvious side effect: it raises the daily search limit to 10 and enables live availability. It omits what happens on failure, whether SMS sends are throttled or cost-bearing, and whether the raised limits are permanent.

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 with zero waste; the prerequisite is stated before the benefit, so the agent gets ordering and consequence in a single read.

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 one-parameter tool with no output schema and no annotations, the description covers the action, precondition, and side effects. The main remaining gap is the implied two-step flow with confirm_phone, which the agent must infer from sibling names.

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% and the single parameter already documents the E.164 format with an example. The description adds no further meaning about the phone argument, so the baseline of 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?

The description states a concrete verb and resource ('Send a code by text message to the client's phone'), which is clearly distinct from confirm_phone and verify_email. It does not explicitly name the sibling it pairs with, but the send-code action is unambiguous.

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?

A prerequisite is stated explicitly ('Requires a verified email first'), which is genuinely useful ordering guidance. However, there is no mention of the natural follow-up (confirm_phone), no when-not-to-use case (e.g. phone already verified), and no guidance about resending or rate limits.

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