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

Annotations already declare a safe, read-only, idempotent operation, so the description correctly focuses on behavior beyond that: the check is partial (only forms with supplied figures), and it evaluates thresholds only rather than classifying assets. It does not describe the return format, but the safety profile is fully covered by annotations.

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?

Three tight sentences with no waste: the purpose and form coverage come first, followed by the partial-check condition and the thresholds-only caveat. Every clause carries decision-relevant information.

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 six-parameter threshold checker with fully documented inputs and a read-only annotation profile, the description covers purpose, scope limits, and input-selection behavior. It omits what the result looks like (which thresholds were triggered), but with no output schema this is a minor gap rather than a blocking one.

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%, and each parameter already documents its form mapping, units (USD), and timing (year-end vs. any time in the year), so the schema carries the semantic load. The description only adds a pointer ('the descriptions of each input say what to include'), which is helpful framing but not new parameter meaning.

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 names a specific verb ('Checks') and a precise resource ('foreign-asset figures against the filing thresholds'), and enumerates the three distinct forms covered (FBAR/FinCEN 114, Form 8938, Form 3520). This clearly separates it from siblings like estimate_federal_tax or list_federal_tax_deadlines.

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 states an explicit usage condition ('Only the forms whose figures are given are checked') and a clear exclusion ('it does not decide which accounts or assets count'). It stops short of naming an alternative sibling for when this tool is the wrong choice, but the scope boundaries are well defined.

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