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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds the inspection targets, which is useful context, but says nothing about failure modes (expired cert, unreachable host) or how results are reported.

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 sentence with no filler, front-loaded with the resource being examined and followed by the three result facets. Appropriately sized for a one-parameter read tool, though it offers no routing context to justify anything beyond the minimum.

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 usefully sketches the return shape (days remaining, chain validity, hostname match). However it omits what happens on connection failure or an invalid certificate, which an agent calling a network-dependent check would benefit from knowing.

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 (url) with 100% schema description coverage, so the schema already explains that http(s) URLs or bare hostnames are accepted. The description adds no further parameter meaning; baseline 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?

States the resource precisely (TLS certificate for the host) and enumerates what is examined (days remaining, chain validity, hostname match), which cleanly separates it from siblings like check_domain or check_url. It lacks an explicit verb ('check') but the intent is unambiguous.

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?

No statement of when to reach for this tool versus the other stillindexed checks, no exclusions, and no note that it targets TLS specifically rather than general domain health. Usage must be inferred entirely from the purpose sentence.

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