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

Annotations already establish read-only, idempotent, non-destructive behavior, so the bar is lower. The description adds valuable behavioral context beyond annotations: the risk thresholds (30%+ high, 15%+ medium) and the fact that payment burden is normalized to a daily equivalent before comparison.

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?

A single front-loaded sentence with no filler. Every clause contributes either the core measurement, an output field, or a decision threshold.

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 simple three-parameter read-only calculation with an output schema and full schema coverage, the description is nearly complete: it explains the calculation basis, normalized outputs, and risk thresholds. A minor gap is that it does not explicitly state the daily-vs-weekly conversion rule or business-day assumption, though the schema covers frequency.

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 three parameters are already documented, including the daily/weekly enum. The description adds only marginal param-level meaning by implying weekly payments are converted to a daily-equivalent before ratio calculation; otherwise it relies on the schema.

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?

It uses a specific verb and resource ('Measure how heavy an MCA payment is against average daily revenue') and enumerates the exact outputs. It is clearly distinguishable from siblings like calculate_mca_apr (cost of capital) and estimate_mca_payoff (payoff timeline).

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?

Usage is implied by the stated purpose and output fields, but the description never says when to choose this vs calculate_mca_apr or estimate_mca_payoff, nor does it state prerequisites or exclusions. An agent can infer the use case but is not explicitly routed.

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