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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the agent knows this is a safe read operation. The description adds the scoping detail 'on your account' but does not cover return format, pagination, rate limits, or behavior when filters are applied.

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?

A single sentence with no wasted words, front-loaded with the core action and resource. It is efficient, though extremely terse for a tool with five optional filters and many siblings.

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 list tool with five optional filters, many sibling list/search tools, and no output schema, the description is too thin. It omits return structure, default ordering, pagination behavior, and how filters combine, leaving the agent without enough context to call it correctly beyond a basic listing.

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 description coverage is 60% (q, pool, and customer_id have descriptions; tag and mode do not). The description itself mentions no parameters and adds no meaning beyond the schema, leaving tag and mode entirely undocumented across both the schema and the description.

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 verb ('List') and resource ('phone numbers') with scope ('on your account'), which distinguishes it from search_available_numbers (which finds numbers to purchase). However, it does not explicitly name any sibling tool or clarify how it differs from get_number or list_number_pools.

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?

Provides no when-to-use guidance, no alternatives, and no prerequisites. The implied usage is to view owned numbers, but the description does not explain when to use this instead of get_number (for a single number) or search_available_numbers (to find new numbers).

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