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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so safety is covered. The description adds useful behavioural context beyond that: it is a pure estimate, minimal input is required, and every unstated assumption has a default, which tells the agent the call cannot fail on missing optional data.

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?

Two sentences, output summary first and the minimal-input requirement second, with no filler. The agent gets the what and the how in minimal reading time.

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, the description helpfully enumerates what comes back (missed calls, lost callers, lost customers, monthly and five-year loss, recovery estimate). Combined with defaulting behaviour this is nearly complete; only the when-to-use routing against sibling calculators 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 description coverage is 100%, so all ten parameters — including the calls_per_week vs missed_per_week precedence and the optional customer_lifetime_value_usd — are already documented in the schema. The description restates the calls/missed choice and the job-value requirement but adds no syntax or unit detail beyond it, so the baseline 3 applies.

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: it estimates annual revenue lost to unanswered calls and the recoverable share via an AI receptionist. That scope is distinct from sibling calculators like calculate_manual_work_cost, so an agent can route correctly without opening the 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?

It tells the agent what inputs are needed ('calls per week or missed calls per week and the average job value') and that other assumptions default. However, it never states when to pick this tool over the neighbouring ROI/cost calculators, so tool selection is only implied.

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