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 safety profile is fully covered structurally. The description adds useful context beyond that: results are scoped to 'this Widely seat' and include the supplying provider and capability. It does not mention pagination or any filtering behavior, so this is a moderate add rather than a rich one.

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 front-loaded sentence that packs the verb, the resource list, the scope, and the extra returned metadata with no filler. Efficient and well-structured, though the dense enumeration makes it slightly list-like rather than hierarchical.

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 read-only listing tool with full annotation coverage and no output schema, the description does the important remaining job of telling the agent what comes back (numbers, caller IDs, SIMs, extensions, eSIMs plus provider/capability). The main gap is the absence of routing guidance against the other list/search number tools.

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 100% and the single parameter (include_shared) is fully documented in the schema, including the Business-plan prerequisite. The description adds nothing about parameters, so the baseline 3 for high-coverage schemas applies.

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 ('Returns') and enumerates the exact resources returned (phone numbers, caller IDs, SIM numbers, PBX extensions, eSIMs), scoped to 'this Widely seat'. Clear on its own, but it does not differentiate itself from list-oriented siblings such as list_did_numbers, list_pbx, or search_numbers, which an agent might reasonably confuse it with.

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?

There is no when-to-use guidance, no exclusion, and no named alternative among the many list_* and search_numbers siblings. The agent must infer usage purely from the enumeration of returned resources.

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