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

No annotations are provided, so the description carries the full burden and does disclose meaningful behavior: DKIM selector discovery 'across common selectors', a composite scoring step, and concrete fixes. It also surfaces the x402 price ($0.02/call, USDC on Base) which is real operational context. It stops short of stating rate limits or explicitly confirming read-only behavior beyond the 'audit' framing.

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 the core capability and the component list before rationale. Slightly redundant ('one call instead of five' and 'in one report card' restate the same idea) and contains a casing typo ('sPF'), but no sentence is dead weight and the pricing note 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 single-parameter read-only tool with no output schema or annotations, the description conveys the full scope of what the audit returns (component grades, composite score, fixes) and the cost model. Complete enough to call correctly; only the absence of any rate-limit or auth detail keeps it from a 5.

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 100% and there is only one parameter, so the schema already fully documents 'domain' (baseline 3). The description only restates 'for a domain' and adds no format or validation nuance beyond the 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?

States a specific verb+resource (email authentication audit for a domain) and enumerates exactly what it covers: MX reachability, SPF grade, DKIM selector discovery, DMARC grade, and a composite score. The 'one call instead of five' framing cleanly distinguishes it from the sibling single-purpose tools (security_spf_check, security_dmarc_check, security_mx_lookup).

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?

'One call instead of five' and 'Use this when an agent needs SPF + DKIM + DMARC + MX in one report card' give clear context for selection. It implies the alternatives (the individual security_*_check tools) but never explicitly states when NOT to use it, e.g. when a single check is all that's needed.

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