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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It transparently describes the computation and the 60% clearance threshold concept, explaining that obstructions within 60% cause significant signal degradation. It does not mention any destructive actions, side effects, or authentication needs, but as a pure calculation tool, none are expected. The description adds valuable context beyond a simple calculation statement.

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?

The description is remarkably concise: two sentences plus a final relational sentence. The first sentence immediately states the core purpose ('Calculate the Fresnel zone radius at the midpoint of a radio link'), which is front-loaded. Every sentence adds value—inputs, outputs, practical significance, and relation to link_budget—without any fluff.

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 calculation tool with a well-defined input schema and an output schema (implied), the description provides complete context: it explains what the tool does, what inputs are needed, what outputs are returned (including the 60% threshold), and how it fits into a broader engineering workflow. It also briefly educates on the first Fresnel zone concept. Given the tool's complexity, this is comprehensive.

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?

The input schema already provides comprehensive descriptions for all three parameters (freq_mhz, dist_km, zone_number) with constraints and defaults, achieving 100% coverage. The description adds context about the first Fresnel zone and the 60% threshold, but does not elaborate on individual parameter semantics beyond what the schema provides. According to the rubric, high schema coverage sets a baseline of 3, and the description does not significantly elevate this.

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 description clearly states the action: 'Calculate the Fresnel zone radius at the midpoint of a radio link.' It specifies inputs (frequency, distance, zone number) and outputs (radius in metres and feet, plus 60% clearance threshold). The verb 'Calculate' paired with the specific resource 'Fresnel zone radius' makes the purpose unambiguous. While it doesn't explicitly differentiate from siblings like fspl or link_budget, the focus on Fresnel zone is unique and distinct.

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?

The description implies usage context: it feeds into link_budget for path clearance analysis, suggesting it is a component in a larger workflow. However, it does not provide explicit guidance on when to use this tool versus alternatives (e.g., fspl for free-space path loss, or link_budget for overall analysis). There are no 'when not to use' statements or exclusions, leaving some ambiguity for the agent.

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