email_check_dane

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

With no annotations, the description carries the full burden. It discloses the tool's behavior in detail: resolves MX records, performs raw DNS queries to _25._tcp.<mx-host>, reports certificate usage/selector/matching type, and flags missing TLSA or DANE-without-DNSSEC. This provides solid transparency beyond the basic input schema, though it does not explicitly note read-only behavior or potential failure modes.

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 four sentences long, each adding essential information: purpose, method, outputs, and special flags. There is no redundancy or filler. It is well-structured, starting with the high-level purpose and then detailing the process.

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 tool's complexity (a DNS query for TLSA records) and lack of output schema, the description sufficiently covers what the tool does and what it returns. It explains the query target, the resolved data, and the edge-case flags (missing TLSA, DANE without DNSSEC), making it complete for an agent to select and invoke 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?

Schema coverage is 100% (the 'domain' parameter has a description). The tool description adds value by explaining that the domain is used to obtain MX hosts, which is not fully explicit in the schema. This clarifies how the parameter is interpreted and used.

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 the tool's purpose: 'Check DANE/TLSA records for a domain's MX hosts.' It uses a specific verb ('Check') and resource ('DANE/TLSA records'), differentiates from sibling tools (e.g., email_check_spf, email_check_dkim) by focusing on DANE/TLSA, and even details the process of resolving MX records and querying TLSA.

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 implicitly conveys when to use this tool (when checking DANE/TLSA for a domain's MX hosts) but does not explicitly mention alternatives or exclusions. No 'use instead' recommendations are given, but the clarity of the purpose makes the usage context obvious. It lacks explicit when-not-to-use guidance, so not a 5.

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