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

Annotations already declare readOnlyHint=true and destructiveHint=false, covering safety. The description adds value by specifying the HTTP method (GET), the auth requirement (No key), and the response fields (billing test/gated and runner_ready). This is beyond the annotations and provides useful behavioral context without contradiction.

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 a single sentence that packs essential information: the endpoint, its purpose, the auth requirement, and the key response fields. It is front-loaded with 'Public readiness' and leaves no waste. Every part earns its place, making it highly concise and well-structured.

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 health check with annotations covering safety, the description is complete. It provides the HTTP method, the path, the auth context, and the response shape. An agent has everything needed to call it correctly without missing information.

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, so the schema already documents everything (vacuously). The description doesn't need to add parameter details; it correctly focuses on the endpoint and response. With no parameters, this is a baseline of 4, and the description appropriately avoids redundant parameter information.

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 clearly identifies the tool as a health/readiness check for the /health endpoint, specifying it returns billing status and runner_ready. It distinguishes itself from the sibling tools, which are all credit-related, by describing a public readiness endpoint. The verb is implicit (GET) but the resource and intent are clear.

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 states 'Public readiness' and 'No key,' indicating this is a public health check with no authentication. However, it does not explicitly provide when-to-use vs. alternative tools or mention exclusions. It gives enough context to infer its purpose but lacks explicit routing guidance.

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