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

With no annotations provided, the description carries the full behavioral burden. It discloses the 10-minute expiry, 5-try limit, error response shape (`invalid-code` with `attemptsLeft`), invalidation on the fifth wrong attempt, and the replace-only-one-number-per-agent rule. This is thorough and honest.

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 dense sentences deliver all key behavioral constraints and the core action with no filler. Critical details like limits and replacement behavior are front-loaded and easy to scan.

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?

The description covers the operation's purpose, failure modes, retry behavior, and a critical one-number-per-agent constraint. It does not describe the success response, but that omission is minor given the single parameter and low complexity.

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?

The schema already documents the code parameter with a six-digit pattern and description. The tool description adds context by identifying the code as the one link_phone texted, reinforcing the source and meaning of the parameter.

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 action ('Spend the code that link_phone texted') and outcome ('tie this agent to that number'), clearly differentiating it from link_phone, which initiates the process. The purpose 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?

The description clearly signals when to use the tool: after link_phone sends a code, to complete the linking. It also explains when to restart via link_phone after exhausting attempts, though it does not explicitly contrast with unlink_phone.

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