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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is known. The description adds meaningful behavioral context beyond the annotations: the session prerequisite and the dependency on a prior search_list call. This is useful operational information that the structured metadata does not convey.

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 description is two sentences with no filler. It front-loads the critical prerequisite, then states the action and parameter source. Every clause earns its place.

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 read-only detail lookup with 100% parameter coverage and clear annotations, the description is largely complete: it covers the login prerequisite, the required identifier, and how to obtain that identifier. The only minor gap is the absence of explicit return-field details, but the phrase 'detailed information' plus the absence of an output schema makes this acceptable.

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 both parameters, including the etan format and how to obtain it. The description repeats the etan sourcing but does not add new semantic meaning beyond what the schema already provides. A baseline of 3 is appropriate here.

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 states a specific verb and resource: 'Get detailed information for a specific e-tax invoice by its 승인번호 (etan).' It also references the sibling search_list tool as the source of the etan, which distinguishes this detail-retrieval tool from list/search/statistics tools.

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 clearly establishes usage context: it requires a prior hometax__session__login call with the same account_link_id, and it explicitly tells the agent to obtain etan from hometax__etax__invoice__search_list results. It does not explicitly state when-not-to-use or compare against search_statistics/search_summary, but the context is unambiguous.

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