dossier_mx

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

Without annotations, the description discloses key behaviors: queries Cloudflare DoH, follows CNAME aliases, 5s timeout, and return format (discriminated union with success/error). Could additionally mention any rate limiting or idempotency, but overall strong.

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?

Three sentences with no redundancy. Purpose, usage guidance, and technical details are efficiently front-loaded and each sentence earns its place.

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 simple tool with one parameter and no output schema, the description covers everything needed: purpose, behavior, return structure, and usage context. No gaps given the 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% for the only parameter (domain), and the tool description repeats this. The schema explains the domain format thoroughly, so the description adds little beyond the already complete schema.

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 action (look up MX records) and result (sorted by priority). It distinguishes from sibling tools like dns_lookup and other dossier_* tools by specifying that this returns a ranked view, not raw DNS.

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?

Explicitly states when to use (verifying inbound-mail routing, precursor to SPF/DMARC) and when not (prefer dns_lookup for raw answer). Provides an alternative sibling tool, which is exemplary.

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