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

Annotations only carry coarse flags (readOnlyHint=false, destructiveHint=true); the description concretizes them by disclosing that the call files an irreversible application with the NTS, creates a receipt record (cvaId + rcatNo), and offers no cancel action. It also reveals the safe preview path before the irreversible step — exactly the behavioral context annotations cannot express. No contradiction with annotations.

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?

Four sentences, each substantive: prerequisite, purpose, irreversibility warning, and the two-step confirm discipline. Nothing is wasted and the most critical constraint (prior login) is front-loaded. The heavy ALL-CAPS emphasis is stylistically loud but not redundant.

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?

For a high-stakes irreversible filing tool with 8 parameters, the description delivers the critical behavioral context (login prerequisite, preview-before-confirm, no cancel) while the schema carries parameter documentation at 100%. Mentioning the receipt record (cvaId + rcatNo) partially compensates for the absent output schema. Code-valued parameters lack enumerations, but that is a schema gap, not a description gap.

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 baseline of 3 applies — all 8 parameters are already documented in the schema. The description's confirm-workflow guidance overlaps with the schema's own confirm parameter description and adds no new meaning for the other parameters (adrOpYn, amtOpYn, cvaDcumGranMthdCd, etc.).

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?

'Apply for VAT Standard Certificate' states a specific verb and resource, and naming the certificate type distinguishes it from sibling apply tools (business_registration, financial_statement, tax_payment_record). However, this differentiation comes primarily from the tool name/title itself; the description largely restates the purpose rather than adding new distinguishing context, 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?

The description gives a clear prerequisite (prior hometax__session__login with the same account_link_id) and a precise invocation sequence (call without confirm for a preview, show the user, then retry with confirm=true), plus an explicit prohibition against autonomous confirmation. It does not name sibling alternatives or state when-not-to-use, but the workflow and precondition provide clear usage context.

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