check_smtp_tls

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

Annotations already declare readOnly, openWorld, idempotent, and non-destructive behavior, and the description complements them with concrete operational details: it opens TCP 25, runs EHLO and STARTTLS, connects and quits without sending mail, may take 10-30 seconds, and requires no auth. It also discloses output contents such as per-MX cipher/version, cert SANs, and FCrDNS verdict, going well beyond the structured metadata.

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 compact, front-loaded with the core action, and every sentence contributes new information: scope, methodology, safety, output, use case, performance, and auth requirements. There is no redundancy or 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?

For a single-parameter tool with no output schema, the description is remarkably complete. It explains the operational behavior, the network interactions, the return values, latency expectations, authentication, and the intended pairing with a sibling tool. No critical context required for correct selection or invocation is missing.

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?

There is only one parameter, domain, and the schema already documents it thoroughly with constraints and an example. The description adds contextual value by explaining the check operates on every MX host, but it does not need to repeat or elaborate on the parameter syntax. With 100% schema description 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 starts with a specific verb and resource: 'Live check of every MX host'. It enumerates the exact checks performed (TCP 25, EHLO, STARTTLS, certificate validation, DNS lookups) and clearly distinguishes itself from sibling tools by naming check_mta_sts as the policy-layer counterpart. This is a precise, unambiguous statement of what the tool does.

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 an explicit use case: 'Use to verify inbound mail TLS posture' and recommends pairing with check_mta_sts for policy-layer validation. It also warns about slower runtime (10-30s) and notes that it is read-only, helping the agent decide when to invoke it. However, it does not explicitly state when not to use it or name alternative tools beyond check_mta_sts.

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