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

Annotations already declare readOnlyHint and openWorldHint, and the description stays consistent with them while adding genuinely useful context: measurements come from Cloudflare's edge (so results reflect that vantage point), redirect chains are followed, and no API key is needed. It stops short of stating timeouts, rate limits, or failure modes.

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?

A single front-loaded sentence with the core purpose first and the return payload enumerated after. The long parenthetical list of security headers is dense but every item is informative rather than filler.

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?

With no output schema, the description carries the burden of explaining return values and does so thoroughly: status, latency, redirects, content info, server header, security headers. What remains unaddressed is failure behavior (unreachable host, timeout) and any output shape.

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?

Only one parameter, and the schema already documents it at 100% coverage with a format example. The description adds no syntax or edge-case detail (e.g., whether bare domains are accepted or non-http schemes rejected), so the schema baseline of 3 applies.

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?

Opens with a specific verb and resource: 'Check right now whether a website/URL is up', then enumerates the exact measurements returned. 'Right now' implicitly distinguishes this point-in-time check from start_uptime_monitor, but no sibling is named explicitly.

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?

'Check right now' implies a one-off check versus the monitoring sibling, and 'Free, no key' tells the agent there is no auth prerequisite. However, it never states when to prefer check_websites (batch) or start_uptime_monitor (ongoing), leaving the agent to infer the boundary.

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