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

With no annotations, the description carries the full burden and does so: it discloses cost ($0.25 USDC per call), output volume caps (30 observations, 30 changes, 64 KiB), and explicit negative guarantees (no raw snapshots, descriptions, schemas, pay-to values, ranges, or pagination). This is unusually complete behavioral disclosure for a paid tool.

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, front-loaded with purpose and scope before constraints and price. Every clause carries information (window, caps, exclusions, cost) with no 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?

There is no output schema, so the description must describe returns, and it does via volume caps, size limit, and exclusion list. It stops short of saying what a 'derived daily observation' or 'material change' contains, which is the one remaining gap for a no-output-schema tool.

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 the schema already specifies a single canonical HTTP(S) URL with wildcards/bulk selectors rejected. The description echoes 'exact x402 resource' but adds no syntax, format, or validation detail beyond the schema, so the 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?

States a specific resource ('exact x402 resource history') plus the exact scope ('latest complete 30-day window'), which goes well beyond restating the name. Sibling tools are all unrelated utilities (dns, lei, rdap, vat), so no intra-family differentiation is required; the only missing element is any explicit contrast with a list/bulk variant.

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?

Use is implied by the scope statement: call this to get history for one resource. It never states when to use it versus an alternative, and the only constraint given (wildcards/bulk selectors rejected) is already framed as a per-call input rule rather than usage guidance.

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