check_dane

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, lowering the bar. The description adds meaningful behavioral context by detailing the MX resolution and TLSA lookup at _25._tcp.<mx-host>, and the DNSSEC-backed verification purpose. This goes beyond the annotations without contradicting them.

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 (four sentences) and front-loaded with the core purpose. Every sentence adds value: functionality, mechanism, usage trigger, alternative tool, and audit context. No wasted words.

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?

Given the availability of an output schema and annotations, the description covers all necessary aspects: the exact DNS lookup procedure, the security rationale, when to use it, and how it differs from the HTTPS variant. It is complete for a DNS-checking tool of this complexity.

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 100%, so baseline is 3. The description adds context about the domain parameter (MX hosts, port 25) but does not provide additional syntax or meaning for 'format' or 'force_refresh' beyond what the schema already explains. It is adequate but not enriching.

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 states a specific verb ('Check') and resource ('DANE/TLSA certificate pinning for SMTP at port 25'), and distinguishes from the sibling tool check_dane_https by explicitly mentioning port 25 and HTTPS port 443. This makes the tool's purpose 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?

Explicit guidance is provided: 'Use when asked if SMTP connections are protected by DANE/TLSA pinning' and 'For HTTPS DANE at port 443, use check_dane_https instead.' Also notes it is 'Part of the scan_domain audit,' giving clear context for when to invoke this tool.

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