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

Annotations already cover read-only, idempotent, open-world, and non-destructive traits. The description goes beyond by detailing the per-row return fields (status indicator, status line, incident count, degraded component count), the roll-up categorization, and handling of unreachable vendors. This adds meaningful behavioral context that the annotations don't provide.

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, each earning its place. The first sentence states the action and output; the second lists practical use cases. No filler or redundancy. The description is front-loaded with the core purpose, making it scannable.

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?

Since there is no output schema, the description compensates well by specifying the exact row fields and roll-up behavior. It also addresses the failure case ('could not be reached') and covers realistic usage scenarios. A minor gap is not specifying the range of status indicators, but the roll-up naming implies them.

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 input schema already describes the single parameter thoroughly: vendor names/keys or hostnames with dot detection and a 1-20 entry limit. The tool description merely restates that it takes a list of vendor names or hostnames, adding no new semantic detail. With 100% schema coverage, the baseline of 3 is appropriate.

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 a specific verb and resource: 'Check the live service status of several vendors at once.' It immediately distinguishes itself from single-vendor siblings like statuspage_check by emphasizing multi-vendor capability, and the phrase 'are any of my providers down right now?' makes the purpose instantly relatable.

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 enumerates explicit use cases: 'dependency health sweeps, incident triage across a stack, and monitoring a set of upstream APIs in one call.' It does not name alternatives or state when not to use it, but the multi-vendor framing clearly implies that for a single vendor you'd use the single-check sibling. This is clear context without exclusions.

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