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

Annotations already declare destructiveHint=true and idempotentHint=false, but the description adds real context beyond them: this creates a *request* record, not a live number, and provider ordering/assignment requires operator approval. That materially changes agent expectations about the effect of a 'destructive' call. It stops short of explaining permissions, rate limits, or what the returned request looks like.

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 efficient sentence with the core action front-loaded and the caveat trailing. It is appropriately sized, though the phrase 'managed phone-number request' is somewhat jargon-dependent for an unfamiliar agent.

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 10-parameter, non-idempotent, destructive creation tool with 10% schema coverage and no output schema, the description is thin. It does not explain parameter expectations or how to follow up on the request (e.g., checking status or listing numbers), leaving substantial gaps an agent must guess at.

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 only 10% across 10 parameters, so the description carries the burden — and it provides zero parameter guidance (no mention of country, project_id, number_type, capabilities, or the org-scoping rule encoded only in organization_id). Adding only a high-level noun phrase leaves most parameters semantically opaque.

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 gives a specific verb+resource: 'Create a managed phone-number request.' An agent can distinguish this from read-oriented siblings like get_number_catalog or list_numbers, since it clearly creates a request entity. However, it does not differentiate itself from adjacent siblings such as check_number_requirements or get_coverage, which also sit in the number-provisioning space.

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 explicit when-to-use guidance and no named alternatives. The clause about operator approval describes a downstream process, not when an agent should choose this tool over check_number_requirements or get_number_catalog. Usage must be inferred entirely.

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