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

Far exceeds the annotations: it discloses the double opt-in flow ("nothing starts until they click it"), what the watcher receives, monthly liveness checks, the 15th-of-month change emails, quarterly confirmation emails, and the exact follow semantics for toll free vs local numbers. This is exactly the behavioral context annotations cannot carry.

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?

The content is relevant but delivered as a single sprawling run-on sentence chain with multiple colons and nested clauses, making it hard to parse. Front-loading is decent but the phrasing ("a number they want that someone has today") is needlessly convoluted.

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?

An output schema exists, yet the description still notes what the call returns, and it fully covers the confirmation lifecycle, cadence of notifications, and the tool's limits. Nothing an agent needs to call this correctly is missing.

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%, so all three parameters are already documented, giving a baseline of 3. The description adds useful meaning for the number value (toll free variants tracked across all 7 area codes, local variants across the state) but says nothing about the name parameter beyond the schema.

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 opening states a specific verb and resource ("Set up a notification about a toll free or local phone number") and explains the two scenarios it covers. It also carves out scope with "It can't buy or reserve a number," implicitly separating it from request_vendor_number, though it never names a sibling directly.

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?

"Use it when the person asks to be told about a number and gives their email address" gives a clear triggering condition, and the negative "can't buy or reserve" rules out the purchase path. No sibling is named as an alternative, so the routing is implied rather than explicit.

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