index_rebuild

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

Annotations cover the safety profile (destructiveHint=true), and the description adds substantive context beyond them: that the entire index is discarded, every embedding is recomputed, and the operation takes minutes on large repositories. The cost/time warning is exactly the kind of behavioral detail an agent needs before invoking a destructive, expensive tool.

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?

Three tight sentences: the operation, its consequence/cost, then the gating condition. Front-loaded with the destructive action, no filler.

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 return values need not be explained, and the description covers the remaining gaps for a zero-param destructive tool: scope of destruction, performance cost, and preconditions. Nothing an agent needs to decide whether to call it is missing.

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, so the baseline is 4. The description correctly introduces no parameter semantics because there are none to describe.

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?

States a specific verb and resource ('Discards the whole index and rebuilds it from scratch') with the distinguishing scope word 'whole' that separates it from an incremental update. An agent can immediately tell this is the full-rebuild path versus the refresh path.

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?

Gives an explicit when-to-use rule with two concrete triggers: 'only when index_status reports an incompatibility, or after changing the embedding model.' It even names the sibling tool (index_status) that gates the decision, leaving nothing to inference.

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