wait_for_mailbox_changes

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

Goes well beyond the readOnlyHint annotation by disclosing blocking semantics, guaranteed return within timeout+grace, early-wake caveat, and correctness of detection even if not early. These are critical runtime behaviors not evident from annotations.

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?

Concise and front-loaded: first sentence states the core action and constraint. Subsequent sentences add necessary caveats without redundancy. No fluff, each sentence 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?

Given the tool's simplicity (2 params, no output schema), the description fully explains purpose, usage constraints, and behavioral guarantees. Complete for an agent to invoke correctly without additional context.

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 both parameters are clearly described in the input schema. The description does not add additional parameter details, so baseline 3 is appropriate.

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?

Clear action: opens an IMAP IDLE session and blocks until a mailbox change event or timeout. Specifies resource (mailbox) and operation (wait). Distinguishes from siblings by focusing on real-time detection without polling.

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?

Explicit use case: 'Use to detect real-time inbox activity without polling.' Provides a clear exclusion: 'do not use in fire-and-forget pipelines.' Also explains timeout behavior, which helps decide when to call.

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