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

Beyond the read-only and idempotent annotations, the description discloses several behavioral traits: no inference or aggregation, snapshot-limited coverage, empty data array on no match, and argument errors on missing/invalid input. These are substantive and not present in the 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?

The description is compact and front-loaded with purpose, then inputs, return format, and behavioral notes. Each sentence is informative, though the final sentences covering required input and errors could be merged for slightly better economy.

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?

Since there is no output schema, the description compensates by naming return record fields (source_class, provenance, snapshot, pagination, limits) and the empty-array behavior. Combined with the detailed schema, an agent has enough to invoke the tool correctly, though the meaning of each return field is only summarized.

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 the baseline is 3. The description adds a high-level mention of year, country, and metric and notes that year is required, but it omits limit, offset, and snapshot from its summary. The schema already fully documents each parameter, so the description contributes little beyond the baseline.

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 ('Find') and a clear resource ('foreign-investment observations') plus filter dimensions (statistical year, country, measure). It states the core action unambiguously, but it does not explicitly differentiate this tool from sibling tools by name.

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 by stating 'Recorded facts only; this query performs no new inference or aggregation' and 'Coverage is limited to the available snapshot', which suggests when raw recorded facts are needed. However, it never names an alternative tool or gives explicit when-to-use / when-not-to-use guidance.

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