Start Email Test

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

Annotations only declare the mutation profile (readOnlyHint=false, idempotentHint=false, destructiveHint=false). The description adds substantial context beyond that: a single-use address valid about an hour for one message, a returned test_id, that every call mints a new address, and that calls count against a daily limit reported in the response.

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-loads the when-to-use trigger, then the return payload, then the required next step. Despite covering several facts, every sentence carries actionable information and none is redundant.

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 fully carries the burden: it explains what is returned (single-use address plus test_id), the validity window, the user-facing instruction, the follow-up tool, and the rate limit. An agent can complete the workflow without guessing.

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 tool takes zero parameters and schema coverage is 100%, so the baseline is 4. The description correctly adds no parameter detail because none exists; there is nothing further for it to clarify.

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 (start an email authentication test) and immediately scopes it to the real-world scenarios it serves: SPF/DKIM/DMARC alignment, spam diagnosis, DKIM proofing. It is cleanly distinguishable from the sibling get_email_test, which it explicitly routes to as the follow-up step.

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?

Gives explicit triggering conditions ('when the user wants to know how a real email from them actually authenticates...') and names the alternative path (call get_email_test with the test_id afterwards). It also surfaces the daily-limit constraint that governs whether a call is appropriate.

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