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

Annotations already declare read-only/idempotent/non-destructive, and the description adds substantial context beyond that: gate ordering, the per-org allowlist plus always-on high-risk-country hard block, that the `stage` field identifies which gate answered, and that no reserve, charge, or review row is written. This is exactly the value-add behavioral detail annotations cannot carry.

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?

Front-loaded with the purpose and outcome enum, then details gates and scope limits in a tight sequence. The sentences are dense but every clause carries distinct information (ordering, exclusions, return field). Slightly heavy for a single paragraph, but nothing is wasted.

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 no output schema and 15 params, the description still explains the return states (allowed|blocked|needs_review), the `stage` field, the gate ordering, and the exact scope boundaries of the check. An agent has enough to invoke and interpret it correctly despite the schema's low coverage.

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 only 33%, so the description has to compensate. It maps the key params to gates (country/channel/profile/caps at the capability gate; purpose and user_authorization at the per-call policy gate; caller-number readiness), adding ordering semantics beyond the schema. Several params (metadata, categories, campaign_id, amount_minor, phone_number, relationship) remain unexplained, keeping it short of a 5.

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+resource ('Preflight a call/SMS') and the exact outcome space (allowed|blocked|needs_review), and positions it relative to create_outbound_call ('before placing it'). An agent can distinguish it from create_outbound_call and the policy/number-rule siblings without opening any schema.

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?

Clearly frames the usage context ('before placing it') and names create_outbound_call as the action it previews. The 'Not a full admission' sentence explicitly carves out number rules, concurrency, and wallet reserve, steering the agent elsewhere, but it does not name the specific sibling (e.g. check_number_requirements) for those unchecked gates.

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