check_email_security

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

The description states 'Read-only' and 'No auth, ~3-8s', which complements the annotations (readOnlyHint, idempotentHint) by adding latency and auth context. It doesn't explain the return format or how the aggregated score is computed, but with strong annotations covering safety, this is adequate. The description adds meaningful context beyond the annotations without contradicting them.

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?

The description is a single, well-structured paragraph that front-loads the core purpose, details the components, then provides usage guidance. Every sentence adds value, with no filler or redundancy. It's appropriately sized for the tool's complexity.

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 tool with rich annotations and 100% schema coverage, the description is complete. It covers purpose, components, usage alternatives, and operational details (no auth, ~3-8s). There's no output schema, but the description explains the aggregated output (0-100 score with prioritised issue list), so an agent knows what to expect. This is fully sufficient for the agent to select and invoke correctly.

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?

The schema covers the single parameter (domain) with 100% coverage, including format constraints (maxLength 253) and an example description. The description reinforces 'domain' usage by implying a domain input, but the real value is in the schema. Baseline for high coverage is 3, and the description adds a bit more by framing the domain as the input to the combined check, so a 4 is warranted.

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 ('combined email-security check') and clearly lists the resources and scope: SPF parse, DKIM selector discovery, DMARC policy validation, MX IP blacklist status, and an aggregated 0-100 score. It explicitly distinguishes itself from sibling tools by naming check_spf, discover_dkim, check_dmarc, and check_blacklist, which is perfect for an agent deciding between tools.

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?

The description explicitly says 'Use for one-shot email security overview' and provides clear guidance on when to use alternatives: 'use check_sender_requirements specifically for Google/Yahoo bulk-sender compliance, or the individual check_* tools when you need only one signal.' This is excellent usage guidance with named alternatives and specific conditions.

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