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

Annotations already establish write/open-world/idempotent behavior, and the description adds substantive context: it returns a report address and exact DMARC record, appends the address to rua= while preserving policy and other report addresses, and notes 24–48 hour report arrival. This is meaningful behavioral detail beyond the annotations.

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?

Four sentences, front-loaded with purpose, then return behavior, apply semantics, and timing. Each sentence adds useful information without repetition.

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 two-parameter tool with full schema coverage, annotations, and an output schema, the description supplies the missing operational context: what is returned, how DNS changes are made, and expected report timing. Nothing essential for correct invocation appears absent.

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 the schema already defines both parameters. The description clarifies apply's effect and the record construction, but adds little parameter-level detail beyond what is already structured.

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 and resource: turn on free DMARC monitoring for a sending domain. It also distinguishes the base action from the optional DNS write via the apply parameter, so the tool's purpose is immediately clear.

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?

Explains when to use apply and that it requires a DNS provider connected in the dashboard. It does not name exclusions or sibling alternatives such as verify_domain or apply_domain_dns, so it stops short of full routing guidance.

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