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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds useful scope context ('cheap checks; no blacklist') but does not say which checks actually run (SPF/DKIM/DMARC?) or what a scan returns, leaving the agent to guess at coverage.

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?

A single short sentence with no filler, and the key scope qualifier follows immediately. It is appropriately sized, though the parenthetical reads slightly like a caveat bolted on rather than structured guidance.

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 one-parameter read-only tool with no output schema, the description covers the essentials. However, 'email health scan' is undefined — the agent cannot tell which checks are included or what the result looks like, which matters for interpreting the output.

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?

There is one required parameter with 0% schema description coverage, so the schema contributes nothing. The description implies the parameter is the domain to scan, which is nearly self-evident from the tool name, but it adds no format, validation, or scope detail.

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: 'Run a domain email health scan'. An agent can tell it evaluates email health for a domain. No siblings exist, so there is nothing to differentiate against, which caps it below 5.

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?

'cheap checks; no blacklist' implies this is the lightweight option and hints at what it excludes, but it never states when to prefer it or what to use for blacklist checks. Usage is only implied, not spelled out.

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