Check the index

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false and destructiveHint=false, so 'Read-only: it changes nothing and needs no input' earns little credit for repeating them. The real added value is disclosing what the check inspects — freshness, possible private-content leakage, and search latency — which the agent could not infer from an empty schema or the annotations, and which matters because there is no output schema.

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 waste: the first front-loads what is reported, the second covers safety and invocation timing. Every clause earns its place and nothing is buried.

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 zero-parameter, read-only diagnostic with no output schema, the description covers what is checked, that no input is needed, and when to reach for it. That is everything an agent needs to select and call it correctly.

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 takes zero parameters, which is the baseline-4 case. The description confirms 'needs no input', consistent with the empty schema, so an agent will not hunt for a required argument.

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 (report) and enumerates the three concrete things it reports: index freshness, private content leakage, and search speed. That is far more specific than the title's 'Check the index' and clearly separates it from the siblings search_notes, open_result and around_result, which retrieve content rather than diagnose the index.

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?

'Use it when results look old or missing, or when the person asks if search is healthy' gives two concrete trigger conditions an agent can match against a conversation. It does not explicitly say when not to use it or name an alternative, but the sibling tools are retrieval tools with no diagnostic overlap, so the boundary is unambiguous.

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