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

With no annotations, the description carries the behavioral burden. It discloses the tool is a simulation, uses public data only, and applies to post-deductible charges, which conveys non-mutating intent and data scope. It stops short of detailing output format or edge cases, but the simulation context makes major behavioral omissions unlikely.

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 tightly organized with WHEN TO USE, WHEN NOT, and EXAMPLES sections. Every sentence earns its place, and the example is directly informative with no filler.

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?

The tool is simple and the description covers when and how to call it. However, with no output schema, it does not state what the function returns (e.g., a dollar amount or a structured breakdown), which an agent would need to interpret the result correctly.

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 documentation covers only coinsurance_rate, so the description compensates by explaining that charge_usd is the post-deductible charge and by providing a concrete example with units ($1K) and rate format. The example clarifies usage beyond the sparse 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?

The description uses a specific verb and resource: 'Simulate member coinsurance exposure' for post-deductible charges. It clearly distinguishes itself from the sibling tool copay_model, which handles flat-copay services.

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 provides explicit WHEN TO USE and WHEN NOT sections, naming the alternative copay_model for flat-copay cases. This gives an agent unambiguous routing guidance beyond mere inference.

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