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

Annotations already establish readOnly/idempotent/non-destructive and closed-world, so safety is covered; the description adds real value beyond that by disclosing what is and isn't judged — purpose, recipient_type and user_authorization are merely recorded, never asserted against. This prevents an agent from treating a rejected result as a judgment on those fields. It still does not describe the shape or verdict semantics of the evaluation response, which matters for a check-only tool with no output schema.

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?

Three tight sentences with no filler, and the most decision-relevant clause (what is checked, and that it must happen before call creation) is front-loaded. The final sentence about country reads as a deliberate scoping carve-out rather than padding, though it partially duplicates the country parameter's own schema description.

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?

With 9 parameters, a nested object, no output schema and only 44% schema coverage, the description carries substantial burden and covers the optional fields well. It leaves the `policy` object and `categories` undocumented and never indicates what the evaluation returns or what an agent should do with a failing verdict, which are material gaps for a pre-flight gate tool.

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 44%, so the description needs to compensate, and it does explain the optional/never-enforced semantics of purpose, recipient_type and user_authorization plus the country boundary — meaningful meaning beyond the schema. However, `policy` (a nested object) and `categories` are left entirely unexplained in both schema and description, and `to` format is only alluded to via 'destination format'.

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?

Names a specific verb and resource (evaluate outbound voice/SMS policy) and enumerates the concrete checks performed: suspensions, caller-number registration, destination format. The temporal anchor 'before creating a call' places it in the outbound workflow, though it never names the adjacent siblings authorize_outbound or create_outbound_call, so the agent must infer the boundary itself.

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?

Gives a clear use condition ('before creating a call') and an explicit exclusion ('destination country is governed by the org's workspace capabilities, not by this evaluation'), which prevents the agent from expecting this tool to gate country eligibility. It stops short of naming which sibling to call instead for country gating, so the alternative is only implied.

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