check_sender_requirements

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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false. The description adds value by explaining that TLS, unsubscribe, complaint rate, and From-header checks are informational follow-ups because they require telemetry, preventing false passes. It also notes the readiness summary is 'explicitly limited.' This goes beyond 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 compact, front-loaded with the core purpose, and every sentence adds value. It covers purpose, scope, limitations, and usage guidance in three sentences without redundancy.

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?

Given the tool's moderate complexity (multiple DNS checks) and no output schema, the description adequately explains what is checked and what is not. It could mention the return format or how results are structured, but the per-requirement pass/fail/warning/info is mentioned. The lack of output schema is partially compensated by the clear description of result types.

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% with a clear description for the single 'domain' parameter. The description adds context by emphasizing the domain-only input (no URL/path/port) and the read-only nature, which reinforces the schema. Since there's only one parameter and it's well-documented, the description adds marginal but useful value.

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 clearly states the tool performs a read-only domain-side preflight against Google/Yahoo bulk-sender requirements, listing specific checks (SPF, DKIM, DMARC, MX, PTR/FCrDNS). It distinguishes itself from siblings by explicitly noting it is domain-side and that message-level requirements are handled by other 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 before a campaign' and directs to 'use analyze_raw_email or create_email_test to verify message-level requirements.' This provides clear when-to-use guidance and names specific alternatives, which is excellent.

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