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

Beyond the readOnlyHint and openWorldHint annotations, the description discloses concrete behaviors: batch size limit, multiple data sources (served certificate, CT logs, RDAP), and the fact that alert lines are Korean. This provides a realistic picture of what the tool returns without contradicting the 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?

Two sentences with no filler. The first sentence front-loads the core behavior and output scope, and the second provides a practical usage hint. Every part 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?

Given one required parameter, safety annotations, and no output schema, the description covers the key details needed to invoke correctly: input limit, output categories, and recommended use case. It leaves little ambiguity for the tool's complexity.

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?

The schema already fully documents the one parameter, 'domains', including min/max items and a description reading 'Domain names,' so schema coverage is 100%. The description mostly restates the up-to-five limit and adds no new semantic detail beyond the schema's existing coverage.

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 clearly identifies the tool as an expiry summary for up to five domains and enumerates the specific checks performed: served certificate expiry/issuer, CT log certificates, RDAP registration expiry, and Korean alert lines. It is distinct in scope from siblings like check_certificate, though it does not explicitly name alternative 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 gives explicit usage context: 'Use this for inventories and periodic checks.' This provides clear context, but it does not state when not to use the tool or name alternatives such as watch_expiry for ongoing monitoring.

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