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

Annotations already declare readOnlyHint=true, so no side-effect warning is needed. The description adds useful behavioral context beyond the annotations by specifying what 'health' means here—reachable, serving, status, and quota state—and the output schema covers return details.

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?

A single, front-loaded sentence that wastes no words and presents the core purpose first. Every phrase ('reachable and serving', 'status and quota state') adds meaning.

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 one-parameter read-only health check with an output schema, the description plus annotations fully cover what an agent needs to invoke and interpret the tool. It states the scope of the check and does not omit required caveats.

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 fully documents the only parameter (id) with a clear description ('Instance (agent) id, as returned by create_instance or list_instances'). With 100% schema coverage, the description is not required to repeat parameter details, and it does not add extra parameter-level meaning.

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 opens with the specific verb 'Check' and clearly identifies the resource ('an instance') and the dimensions checked: reachability, serving status, and quota state. This distinguishes it from sibling tools like get_instance_term or create_instance, which concern different operations.

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 a clear context: use this tool to verify an instance is reachable and serving, and to inspect status and quota. It does not explicitly name alternatives or state when not to use it, though the sibling list makes the contrast evident.

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