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

Adds rich behavioral context beyond annotations: pricing ($0.005), roll behavior for weekends/holidays, roll_unverified flagging when the source is ambiguous, coverage_gap for unverifiable countries instead of invention, and post-200 binding guidance. Annotations only cover safety; the description carries the real behavioral load.

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 resource and value, but the description is dense and runs through pricing, rules, due dates, roll verification, coverage gaps, year_end, free HTML, trial terms, and follow-up binding in one block. Several clauses (e.g., the pricing parenthetical and HMAC push detail) could be trimmed.

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?

Complete for a complex paid data tool: with an output schema present, return values need not be explained, and the description covers scope, pricing, roll logic, error handling (coverage_gap), parameter nuances, and lifecycle (bind get_changes/register_alert). Nothing an agent needs to invoke 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 coverage is 100%, so the baseline is 3, but the description adds meaning: year_end re-anchors year_end_variable corporate-tax rules, which explains a non-obvious parameter interaction. It also implies the from/to window semantics, though the schema already documents these.

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 (recurring statutory tax deadlines) with scope broken out by tax type (VAT/GST, PAYE, CIT) as rules plus due dates. Clearly distinguishable from siblings like compute_vat or get_public_holidays, which are single-purpose calculators.

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 context: it is a paid series, HTML version is free, US series free to try, and it directs the agent to bind get_changes or register_alert afterward. It does not explicitly compare when to call this vs compute_vat or compute_statutory_interest, but usage context is otherwise clear.

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