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

Goes well past annotations: the call 'cannot be recalled', requires the direct:tasks scope, developer opt-in, and per-person consent; calls run Mon–Fri 9:00–17:00 local with a next_window error; no number is dialed twice in 24h and accounts have a daily cap. It also states the return shape and routes progress checks to get_call_result, plus credit cost lookup via get_m2m_network.

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 purpose and tool routing, then constraints, then a worked example — all sentences carry information. It is a dense single block, however, and the eligibility/compliance clauses could be grouped more scannably rather than run together.

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 7-required-parameter destructive action with no output schema, the description covers prerequisites, consent, scheduling, idempotency, return fields, and follow-up tooling. Nothing an agent needs to invoke it safely is missing.

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 already 100%, so the baseline is 3; the description adds genuinely new meaning — number and callback_number must be callable US/Canadian E.164, callback_number is the person's own and never the business's, and message_id must be reused unchanged on retries to guarantee a single call. It does not elaborate on optional questions/max_seconds, keeping it just below 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 and resource ('place an outbound phone call to a business to ask for information on a named person's behalf') and explicitly differentiates from siblings find_business_agent and send_to_business with the exact conditions that select each. An agent can choose correctly 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?

Gives explicit when-to-use ('when find_business_agent returned not_found for a US or Canadian number'), when-not ('when a Direct card exists use send_to_business'), and hard exclusions ('Informational calls only: no sales, payments or account access'). Operating-window behavior and the refusal path are also spelled out.

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