librarian_status

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

With no annotations, the description carries the full behavioral burden, and it does disclose the return content in concrete terms (catalog availability, per-category counts, index age), which implies a read-only diagnostic. However, it never states that the operation is non-mutating, whether it is cheap or expensive to call, or whether it requires a running index service — gaps that matter for a tool with zero annotation coverage.

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, no filler. The capability statement is front-loaded and the parameter note trails it where it belongs. The parenthetical count list is dense but informative rather than 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?

An output schema exists, so the description need not explain the response shape, yet it still previews the categories being counted, which helps the agent decide before calling. For a zero-required-parameter read tool this is close to complete; the only shortfall is the absent guidance on when this diagnostic should be preferred over the other librarian_* tools.

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 0%, so the description must compensate, and it does: it explains that 'caller' is an optional caller label and explicitly instructs to leave it empty. That is more than the bare schema offers (only a default of ""). Minor gap: it does not say why the label exists or when supplying one would be useful.

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 the resource ('librarian') and what the tool reports: catalog availability, index counts across six named categories, and index age. That is a specific, concrete purpose an agent can match to a need. It does not distinguish itself from siblings like librarian_guide or librarian_gap, which is the only missing element.

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?

There is no statement of when to call this versus the other nine librarian_* tools, nor any precondition or follow-up guidance. Only the parameter note ('leave it empty') gives any actionable direction. The status/health framing implies a diagnostic use case, but the agent must infer it.

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