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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive behavior. The description adds valuable behavioral detail beyond annotations: that it actively initiates a network handshake and grades the result, plus what findings it surfaces. This helps the agent understand the real-world side effect despite readOnlyHint.

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 concise, front-loaded sentences with no filler. The first sentence states the core operation and outputs, the second lists key surfaces. Every clause 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?

With no output schema, the description explains the main returned fields (expiry, SAN, self-signed, findings, grade). Annotations cover safety, and the input schema covers the port range and default. It is complete enough for selection and basic invocation, though parameter semantics could be stronger.

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 description coverage is 0%, so the description bears the burden of explaining parameters. It mentions ':443' but does not clarify that 'port' is an overridable parameter or describe that 'domain' is the target hostname. The only parameter it implicitly addresses is the default port, leaving the required domain parameter essentially unexplained.

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 states a specific action ('Open a TLS handshake'), the resource (port 443), and the specific data captured (cert, protocol version, cipher, A-F grade, expiry, SAN, self-signed detection). This clearly distinguishes it from sibling tools like dns_lookup or dns_certificates, which are not live handshakes.

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 conveys that this is a live, active check by explicitly saying 'Open a TLS handshake on :443', implying it is for current TLS posture rather than historical or registry-based DNS data. It does not name alternatives or exclusions, but the live-handshake framing provides clear context for when to use it.

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