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

With no annotations provided, the description carries the full burden of behavioral disclosure. It reveals the resolution of the _mta-sts TXT record, the policy fetch location, the 10s timeout, and the not_applicable result when no TXT is published. This is strong transparency for a network check, though it omits failure modes and side effects.

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 three sentences long, front-loaded with the primary purpose, and each sentence adds value: purpose, use case, and method/timeout/result. There is no fluff or redundant wording.

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 multi-step network check with no output schema, the description covers the key workflow and return semantics (CheckResult and not_applicable case). It could elaborate on what validation entails or error conditions, but the description is sufficiently complete for an agent to select and invoke the tool correctly.

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?

The input schema already documents the single parameter 'domain' with detailed constraints (resolvable public FQDN, rejects IPs/ports/paths/protocols), giving 100% schema coverage. The description adds no parameter-specific semantics, so the baseline score 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 clearly specifies the tool fetches and validates a domain's MTA-STS policy, naming the exact fields (mode, mx, max_age, policy id). It distinguishes itself from sibling dossier tools by focusing on MTA-STS and even states the practical use case of confirming inbound SMTP TLS enforcement.

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?

It provides a clear use case: 'Use to confirm inbound SMTP is locked to TLS for this domain.' This gives context for when to invoke the tool. However, it does not explicitly mention when not to use it or point to alternatives like dossier_tls or dossier_mx, so it lacks exclusions or alternative guidance.

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