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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuinely useful behavior beyond that: empty combinations are explicitly listed as absent (not ingested), and detail=true yields per-source rows while the default is a summary (top 5 source lineages, plus US non-public layer counts). No contradiction with 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?

Two front-loaded sentences, each with a distinct job (what is returned, then how/when to use it), with the availability-check instruction up front. The bilingual JA/EN duplication slightly inflates length, but it is deliberate and structured rather than redundant 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?

An output schema exists, so return-value detail need not be restated, and the description covers the one non-obvious semantic (absent rows mean not ingested). For a 4-param, all-optional availability tool this is nearly complete; it only lacks explicit routing to the follow-up tools to call once coverage is confirmed.

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 all four parameters are already documented, including the detail default/true behavior and enum semantics. The description adds little parameter-level detail beyond what the schema provides, which is the expected baseline-3 case when the schema does the heavy lifting.

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 gives a specific verb and resource: it returns what the JCCDB observation layer holds (rows per country x layer x source, priced rows, status counts, source periods). The 'check availability here before answering' framing separates it functionally from data-returning siblings like get_jccdb_observations, but it never names those siblings explicitly, so differentiation is left partly to inference.

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 a clear when-to-use condition: verify here whether a given country/layer combination has data before answering (the layer param text reinforces this). It stops short of explicit when-not guidance or naming an alternative tool to use instead when coverage exists, so it is clear context without exclusions.

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