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

Annotations already establish a safe, idempotent, closed-world read, so the description's job is to add what they cannot. It does: unsupplied figures receive documented neutral defaults surfaced in an `assumptions` field, and yearly growth/annual churn are compounded into monthly rates — both non-obvious behavioral facts an agent cannot infer from the 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?

Four sentences, each carrying distinct information: what it computes, what it accepts, how gaps are handled, and the one-listing scope limit. Outputs are front-loaded and there is no restatement of the title or schema.

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?

An output schema exists, so return values need not be detailed, yet the definition still previews them. For a 12-parameter tool with full schema coverage and annotations covering safety, the remaining risk — silent defaults and unit conversion — is explicitly addressed.

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, but the description adds meaning the schema lacks: that missing figures are defaulted rather than required, and that defaults are reported back. Precedence rules and unit conversions are already in the field descriptions, so no further credit is due there.

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?

The definition gives a specific verb and resource ('Evaluates a business-for-sale listing') and enumerates the exact outputs produced: valuation range, price position relative to it, and price multiples of ARR and profit. An agent knows precisely what this returns before 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 clarifies the input context (figures a listing states, sourced from Acquire.com, Flippa, or a broker) and constrains scope with 'Evaluates one listing per call.' It does not name the siblings `value_business` or `explain_methodology`, so the boundary between listing analysis and general valuation is left implicit.

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