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

Annotations cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=false), so the bar is lower, and the description adds genuinely useful non-schema context: pricing model, auth paths, the free-trial limit, and a privacy guarantee ('no individual seller identity is returned'). It does not disclose result size, pagination, or latency behavior.

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 payment/pricing sentences earn their place because cost is not captured in annotations or schema, but the opening rhetorical question is pure filler and the core 'what it returns' sentence is buried last. Four sentences with poor front-loading of the primary purpose.

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?

With three optional parameters, full schema coverage, and no output schema, the definition tells the agent the aggregation dimensions and the identity-privacy constraint, which is enough to call and interpret it. It stops short of describing how movers are counted or what a 'size band' looks like.

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 schema already documents window, api_key, and min_usd with ranges and defaults. The description only echoes 'over a window' and 'large settlements' without adding syntax or format detail, so baseline 3 applies.

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 resource and scope: large settlements over a window, aggregated by facilitator, category and size band, plus per-category mover counts. The rhetorical opener ('Where did the large settlements go?') is soft, but the substantive sentence pins down exactly what is returned. It distinguishes itself from siblings by topic (whale/large-settlement flow) without explicitly naming an alternative.

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 gives access conditions (paid via x402 at $0.99/call, Builder/Pro Agent key, or 1 free MCP trial call/day) but never states when to pick this tool over alternatives like get_provider_revenue or get_market_summary. Usage is only implied by the framing question.

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