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

With no annotations, the description carries the full burden. It discloses the tool is 'Free' and returns status, version, and uptime, which is meaningful behavioral context. It doesn't describe response format or error behavior, but for a zero-parameter health check this is reasonably sufficient.

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, and the key behavioral attributes ('Free', returns status/version/uptime) are front-loaded. Every word earns its place.

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 health check, the description covers the essentials: what it returns and when to use it. It could mention error handling or exact output schema, but the simplicity of the tool makes it complete enough. Siblings are clearly distinct.

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 zero parameters, so the baseline is 4. The description adds no parameter-level detail, but none is needed. Schema coverage is 100% trivially since there are no properties.

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 states the tool returns service status, version, and uptime signal, using a specific verb ('returns') and resource. This distinguishes it from siblings like pricing or clean_page, which clearly serve different purposes. An agent can immediately identify this as a health check.

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?

Provides explicit when-to-use guidance: 'Use to check the service is reachable before paying for anything.' This gives a clear context and an exclusion (before paying), making usage intent unambiguous.

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