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

No annotations are provided, so the description carries the full disclosure burden. It does describe the main processing logic (economic/physical nexus), the return components, and the fallback behavior when states_sales is missing. However, it omits important behavioral context such as legal threshold assumptions, whether the determination is advisory, and data freshness or accuracy limitations.

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 well-structured with a clear summary, parameter list, and return summary. Every sentence provides useful information, and the example is concise yet illustrative. It avoids unnecessary repetition despite the title already naming the domain.

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?

Given the two optional parameters, zero required parameters, and the presence of an output schema, the description covers the essential inputs, fallback behavior, and return contents. It lacks explicit legal caveats and sibling differentiation, which prevents a perfect score, but it is sufficient for an agent to invoke the tool 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 description coverage is 0%, but the description fully compensates by explaining both parameters in detail. It defines states_sales with state-code keys, sales amounts, transaction counts, a concrete example, and the default behavior; it also defines has_physical_presence with examples such as warehouses, offices, employees, and return points.

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 that the tool determines US sales tax nexus by evaluating economic nexus and physical nexus, producing a list of states requiring registration plus marketplace facilitator collection tips. This is a specific verb+resource, though it does not explicitly differentiate itself from sibling tools like tax_filing_planner or vat_registration_guide.

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?

There is no guidance about when to use this tool versus the sibling tools, and no exclusions or prerequisites are stated. The only usage-related hint is the default framework explanation returned when states_sales is omitted, which does not help an agent choose between alternatives.

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