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

Despite annotations already flagging openWorld/destructive, the description adds substantial non-obvious behavior: idempotency_key reuse/dedup rules, the day-scoped derived key, caller-ID routing, terminal result statuses, cost of 300 points/minute with a one-minute minimum and no charge on no-answer. That is exactly the kind of real-world side-effect detail the annotation cannot convey.

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?

Dense but deliberately organized: lead sentence, then per-action blocks, then cross-cutting notes on language/idempotency/caller ID/return/cost. Every sentence carries operational weight given a 15-parameter, side-effecting tool; only minor tightening is possible.

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 complex, non-reversible, costly tool the description covers the full calling contract: required inputs per mode, time formats, idempotency, terminal vs in_progress outcomes, handoff to wait_for_call, and billing. An output schema exists, so enumerating result fields in more depth is unnecessary.

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 100%, so the baseline is 3; the description goes further by grouping which parameters are required per action, pinning date/time to merchant local time, and explaining reply_language vs the spoken language and the idempotency_key semantics. It leaves predicted_qa, wait_seconds, special_requests, fallback_instructions and phone_ref to the schema, so it is not exhaustive.

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?

Opens with a concrete verb+resource ('Phone a business and wait for the outcome') and the action-mode breakdown makes the two distinct operational shapes (book vs inquiry) explicit. An agent can separate this from call_person/call_contact/call_me on the 'business' target alone.

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 states when to use each action and routes the agent to wait_for_call for in_progress results, plus gives a do-not-redial rule for failed results. It stops short of an explicit 'use call_person instead when...' sibling contrast, so it lands just under full marks.

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