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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so safety is covered. The description adds real context beyond that: the return is a low/medium/high risk reading, and the rewrite is rule-based and optional, which is behaviorally informative with no output schema present.

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 dense sentence front-loads the action, scope and detection categories, then adds the return shape. No wasted clauses, though the long enumeration makes it slightly heavy for one 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?

With no output schema, the description carries the return-value burden and does so (risk level + optional rewrite). It omits defaults for the zero-required-parameter case and any rate/limit notes, but nothing critical to calling it correctly is missing.

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 coverage is 67%, and the description compensates by clarifying that body accepts plain text or HTML and that rewrite produces a calmer subject plus plain-text body rewrite. This adds meaning beyond the terse schema text for the two most ambiguous parameters.

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 uses a specific verb+resource ("Scan an email subject and body ... for spam-trigger phrases") and enumerates the exact detection categories, making it unambiguous against siblings like analyze_headers or check_domain, which operate on entirely different artifacts.

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?

Usage is implied by context (pre-send email copy review), but the description never states when to prefer this over siblings such as analyze_headers or check_blacklists, nor any preconditions. Adequate minimum-viable guidance without explicit routing.

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