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

Annotations already mark the tool as read-only and non-destructive. The description adds valuable context beyond that: the endpoint is public, keyless, and reports specific states (billing test/gated and runner_ready). It does not describe response format or status codes, but for a zero-parameter health endpoint this is a minor gap.

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 compact sentence that front-loads the purpose and includes the endpoint, public access, and reported fields. There is no wasted wording.

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 simple, zero-parameter, read-only health check with no output schema, the description covers the endpoint, authentication requirement, and core reported statuses. It could clarify what 'test|gated' and 'runner_ready' mean, but the overall context is sufficient for invoking the tool.

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?

There are no parameters, and schema coverage is effectively 100%, so the description carries no parameter documentation burden. The baseline of 4 applies because there is nothing for the description to add about parameters.

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 states a specific resource (GET /health), its public nature, and the readiness information it reports ('billing (test|gated) and runner_ready'). It is distinct from the billing/key/pdf siblings, though the title contains unrelated PDF text that creates noise.

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 implies use for readiness checks and explicitly notes that no key is required, which is useful context. However, it does not explain when to prefer this tool over alternatives or provide any exclusions or preconditions.

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