Wait for an email

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

With no annotations, the description carries the full burden. It usefully discloses the polling cost ('Each poll uses one Mailsac operation') and the return payload, but never states what happens when the timeout elapses (error, empty result, partial match) or whether the call blocks. That failure-mode gap is material for a wait-style tool.

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 core action and then lists the returned artifacts without padding. Slightly overloaded by packing the full return list and the polling-cost note together, but every clause carries information.

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?

No output schema exists, and the description does cover the returned fields, which is the main need. However, for a 6-parameter, timeout-driven tool with zero annotations, it omits timeout/failure semantics and concurrency behavior, leaving a real gap.

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 description coverage is 83%, so the schema already documents address, fromContains, receivedAfter, subjectContains and timeoutSeconds. The description adds no filter syntax or matching semantics beyond 'matching email', so it does not extend the schema meaningfully.

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 ('Poll an address until a matching email arrives') and enumerates what is returned, making it clearly distinguishable from siblings like list_emails and read_email. The purpose is unambiguous without opening the schema.

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 the polling behavior — an agent infers this is for awaiting an inbound message rather than reading one already present — but no sibling is named and there is no explicit when-not guidance. Adequate but leaves the choice against read_email/list_emails to inference.

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