email_check_mta_sts

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

With no annotations, the description carries the full burden. It transparently lists the steps (DNS query, HTTPS fetch, parsing) and the specific flags it produces (testing mode, short max_age, missing policy files). This gives a clear picture of the tool's behavior, though it does not describe auth requirements or rate limits, which are unlikely to be relevant for a read-only check.

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, each serving a clear purpose: stating the function, outlining the process, and listing the parsed/flags fields. It is front-loaded and concise with no redundant words or fluff.

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?

The description thoroughly covers the tool's multi-step process and the types of output (mode, MX, max_age, flags). While there is no output schema, the description gives a strong sense of what the tool returns. It does not specify the exact output format, but this is a minor gap for a check tool.

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 schema description coverage is 100% for the single 'domain' parameter. The description adds no additional semantic detail beyond what the schema already provides, so the baseline of 3 applies. The description merely echoes the schema by mentioning 'for a domain'.

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 checks MTA-STS for a domain, specifying the exact resource and action. It also details the steps (querying TXT record, fetching policy file, parsing fields), which distinguishes it from sibling email tools like email_check_spf or email_check_dmarc.

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 implies usage by its focus on MTA-STS checking, but it does not explicitly mention when to use this tool versus alternatives (e.g., other email security checks). No exclusions or alternative tool references are provided, so the usage context is only inferred.

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