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

Annotations already disclose non-read-only, open-world, non-idempotent behavior; the description adds crucial operational detail: carrier test lines must be dialed within a window, a token must be retained for keyless checks, and billing changes after the first free check. This is substantive context beyond structured fields and does not contradict the annotations.

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?

Four short sentences: purpose first, then returns, required follow-up, and billing. No filler; every sentence carries operational 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 explains the immediate return values (dial lines, check id, token) and external workflow. It still omits how to retrieve the finished result (e.g., via get_check) and the length of the call window, leaving a modest completeness 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?

All four parameters are fully documented in the schema, so the baseline is 3. The description adds little parameter-specific detail beyond workflow context (the number must call test lines; token must be kept), and does not explain carrier selection or webhook behavior beyond what the schema provides.

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 ('Start') and resource ('check') and scopes it to the three carriers, making clear it initiates a new check rather than retrieving one. It does not explicitly name sibling alternatives like get_check, so it falls short of full sibling differentiation.

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?

It explains the required external follow-up (the checked number must call each test line within the window) and the payment prerequisite (first check free; later checks need a key with funds). It does not explicitly contrast with get_check/get_coverage or state when not to use it.

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