list_numbers

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

With no annotations to rely on, the description carries the full transparency burden. It discloses the automatic paging behavior, the per_page cap, the truncation warning, and the distinction between account_status and status. This is meaningful behavioral information beyond what the schema provides, though it stops short of covering error handling or rate limits.

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 description is well-structured: a clear first sentence states the purpose, followed by concise details on output, paging, and filtering. Every sentence adds value and there is no filler. It is neither too terse nor overly verbose.

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?

Given the tool's complexity (7 parameters, some nuanced interactions) and the existence of an output schema, the description covers the most important behavioral aspects: paging, truncation, and account filtering. It does not explain account_ids or name_contains in detail, but these are relatively simple. The description is sufficiently complete for an agent to select and invoke the tool correctly in most cases.

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 0%, so the description must clarify parameters. It explains max_items (paging quantity), per_page (indirectly via cap), account_status (which accounts to search), status (filters numbers by their own status), and number_type (toll-free/local). It does not explicitly cover account_ids or name_contains, but the key parameters are well-defined.

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 clearly states it lists tracking numbers and their routing across sub-accounts, immediately distinguishing it from sibling tools like get_number (single number) and list_sub_accounts (different resource). The verb 'list' plus detailed resource and scope makes the purpose 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 provides clear context on how to use the tool: it explains the default active sub-account filtering, how to override with account_status, and the meaning of max_items for paging. It does not explicitly name alternative tools or state when not to use this tool, but the usage context is strong.

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