What this catalogue actually covers

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

Annotations already declare read-only, idempotent, open-world, and non-destructive behavior, so the description only needs to add extra context. It adds that information is live, includes coverage nuances per region and locale, and explicitly reports what data is NOT present, aligning well with the open-world hint.

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, front-loads the substantive output content, and ends with a pragmatic usage directive. Every sentence carries value.

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 no-parameter status tool with no output schema, the description is complete enough: it explains what information the call returns and when to call it. There is no missing guidance needed to select or invoke this tool.

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 tool has zero parameters and schema coverage is 100%, so the baseline is 4 and there is no parameter information to add. The description correctly avoids inventing parameter documentation.

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 names a specific verb-resource pair ('live counts and coverage for the catalogue') and defines its scope by enumerating content: sets per print region, card total, and locale name coverage. This clearly distinguishes it from sibling card search, pricing, and reference 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 an explicit call trigger: 'Call this before telling a user what the API can and cannot answer.' It does not name alternative tools or say when not to use it, but for a status tool this is a clear and actionable usage context.

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