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

Goes well past the annotations (which only cover read-only/idempotent/open-world safety) by disclosing price ($0.35), the free refusal path with a coverage_gap/no_charge outcome, the shared IP rate limit, the payment requirement when api_key is absent, and that the output is neither a certified series extract nor legal advice. Verification via verify_answer_receipt is also named.

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-loads the critical facts — PAID at $0.35 and the resource — before pricing, coverage, and receipt details. It is dense with parenthetical asides and runs long, but each clause carries information an agent needs, so the length is largely earned.

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 values need no explanation; for a paid, open-world, idempotent query tool the description covers pricing, coverage boundaries, free-refusal behavior, auth/payment paths, and receipt verification. Nothing needed to call it correctly is missing.

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 already 86%, so the schema documents country, from/to, tax, api_key and receipt on its own. The description restates the receipt default and api_key/x402 behavior and adds the certified-extract distinction, but adds little operational meaning beyond what the schema already provides.

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 verb and resource — upcoming VAT, PAYE and corporate-tax due dates in a window — with scope details (weekend/holiday rolling, per-rule citations, verified countries CA/DO/US). An agent knows exactly what comes back. It does not, however, differentiate itself from the close sibling get_filing_deadlines, so it falls short of a 5.

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?

Useful conditions are given (free refusal via coverage_gap when the answer cannot be complete, 3 free calls/IP/day shared with the answer tools, pass api_key or expect an x402 requirement). But it never states when to pick this over the sibling get_filing_deadlines or the other tax tools, so guidance is implied rather than explicit.

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