health-check

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

With no annotations, the description carries the full burden of behavioral disclosure. It does describe the return format ('overall healthy/unhealthy status with a pass/fail line per check') and implies it is non-invasive, but it does not explicitly state whether it has side effects, requires permissions, or if checks are read-only. For a health-check tool, this is adequate but leaves some ambiguity about potential network or system impacts.

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 three short, targeted sentences: 'Use when: ...', 'Returns: ...', and 'Do not use when: ...'. Every sentence provides essential guidance with no fluff or repetition, making it highly concise and well-structured.

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 tool with no parameters and a simple health-check function, the description covers the essential context: when to use it, what it returns, and when to avoid it. The output schema likely details the checks further, so the description is complete enough for this low-complexity tool.

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 has zero parameters, and the schema is empty. The baseline for 0 parameters is 4, and the description adds context by explaining what the tool checks (Mail.app reachability and basic server checks). This is sufficient since there is no parameter detail to compensate for.

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's purpose: 'a quick check that Mail.app is reachable and the server's basic checks pass.' It uses a specific verb ('check') and resource (Mail.app/server), and distinguishes itself from the more detailed 'doctor' tool by emphasizing 'quick check' versus 'detailed diagnostics.'

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 when-to-use and when-not-to-use guidance is given: 'Use when: doing a quick check...' and 'Do not use when: you need detailed permission/account/IMAP/SMTP diagnostics with remediation steps (use doctor).' This clearly directs the agent to an alternative tool, satisfying the criteria.

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