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

Annotations only say it is a non-read-only, non-destructive, closed-world write. The description goes further by disclosing the side effect chain: the domain is registered, saved, and verification is immediately initiated across MX, SPF, DKIM, DMARC and blacklists. It stops short of stating whether the call is idempotent, what happens if the domain already exists, or what auth/plan is required.

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?

Front-loaded with purpose, then verification detail, then routing rules — a sensible order. The verification acronym list is a little dense but is genuinely informative; overall only minor redundancy between the title sentence and the first description sentence.

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 one-param mutation tool with no output schema and thin annotations, the description covers the critical unknowns: what it creates and what verification it kicks off. What's missing is the failure/duplicate-domain behavior and whether the response contains the DNS records the user must publish.

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?

One required parameter with 0% schema description coverage, so the schema provides no format guidance at all. The description never says what 'domain' should look like (bare hostname vs. URL, subdomain handling, max length), leaving the agent to guess. Baseline 3 is the most this earns given the description adds nothing about the parameter.

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?

States a specific verb+resource (connect/register a sending domain) plus the immediate consequence (DNS and deliverability verification). It explicitly separates itself from check_domain and list_domains, so an agent can pick it without opening any schema.

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?

Contains an explicit USE THIS trigger ('setting up a new custom domain to send cold emails from Ballast') and two explicit DO NOT cases with named alternatives (check_domain for testing external/unverified domains, list_domains for listing). Nothing is left to inference.

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