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

With no annotations, the description carries the burden of behavioral disclosure. It explicitly mentions the authentication requirement (sign-in or API token), which is critical. It also describes the return data (availability stats and hourly buckets), providing transparency about the response. Minor gaps like lack of pagination or rate limit details are acceptable for this simple read operation.

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 two sentences, front-loaded with the core purpose, then details on identification and auth. Every sentence earns its place with no repetition or fluff. Excellent structure for quick parsing.

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?

Given no output schema or annotations, the description covers the essential aspects: purpose, input selection, authentication, and response content. It lacks a precise breakdown of the return format, but for a history tool, 'availability stats plus hourly buckets' is sufficient for an agent to infer the response shape. Slightly more detail on the stats (e.g., uptime percentage) would make it complete.

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?

Schema coverage is 100%, so baseline is 3. The description adds value by explaining that monitorId and url are alternative ways to identify the monitor, which is not apparent from the schema alone. This clarifies the relationship between parameters and helps the agent choose the right one. No other additions needed.

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 gets 'uptime and response-time history' for a specific monitor, specifying the resource type (NsLookup.io uptime monitors) and the data returned (availability stats plus hourly buckets). It distinguishes itself from siblings like uptime_check (single check) and my_monitors (list) by focusing on historical data.

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 clear context: it is for historical uptime/response data, and identifies the monitor by id or URL. It doesn't explicitly name alternative tools for current status or monitor listing, but the 'history' framing implies when to use it. Excluding explicit 'when not to use' guidance keeps it one point below a perfect score.

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