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

Discloses a lot beyond the single annotation: 10-40 second latency, refusal behavior when no served series match, the series_limit error tied to the caller's plan, and the key_required error with instructions for obtaining and passing a free API key. It also explains that share=true creates a permanent public page, consistent with readOnlyHint=false rather than contradicting it.

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?

Front-loaded with the core purpose and the computed-answer guarantee; each following sentence carries distinct information (cross-source, plan cap, refusal, latency, auth). It is dense and reads as one long run-on block rather than being broken into scannable segments, which costs some readability.

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?

There is no output schema, so the description carries the return-value burden and does so fully (answer, Plotly chart, Python code, citations, per-series verification badge). Combined with auth requirements, latency, and failure modes, an agent has everything needed to invoke it 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 coverage is high (80%), so the baseline is 3, but the description adds real meaning: it explains that series pins exact series across sources and skips AI resolution, that the joinable-series count is plan-limited, and that share produces a meta.permalink the caller should hand to the user. It does not clarify start/end date semantics beyond the schema's YYYY-MM-DD.

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?

States a precise verb+resource: answer a natural-language question over served official statistics, returning a computed answer, chart, code, citations, and verification badges. It distinguishes itself from read-oriented siblings like get_series or search_catalog by emphasizing cross-source joins and AI resolution, so an agent can tell what unique role this fills.

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?

Gives clear usage context: use it for cross-source joins (e.g. BLS + Statistics Canada + UK ONS in one call), and the optional series param lets callers pin exact series and skip AI resolution. It doesn't explicitly name a sibling alternative or state when NOT to use it, so it stops short of full when/when-not routing.

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