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

Annotations already indicate read-only, idempotent, and non-destructive behavior, but the description adds valuable context: it runs 6 internal checks, reports pass count, does not probe each tool individually, has ~200ms latency, is free, and has a rate-limit caution. No contradictions with annotations; description enriches them substantially.

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 main description is front-loaded with the essential purpose, and each additional section (example, when to use, when not to use, cost, latency) earns its place by helping an agent decide and call correctly. No filler or redundant repetition of schema data.

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 no parameters, no output schema, and rich annotations, the description is fully complete. It explains what the tool checks, how to call it, when to use it, and its operational constraints, so an agent has everything needed to invoke it correctly.

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, so the schema already covers everything. The description adds an example call 'self_test({})' and clarifies that no arguments are needed, which is sufficient for this parameterless tool.

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: 'runs 6 internal checks and reports how many passed,' and explicitly distinguishes itself from sibling tools with 'it does NOT probe each tool individually.' This makes it immediately clear what self_test does and what it does not.

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?

Provides explicit WHEN TO USE guidance: 'at agent startup, before high-stakes task sequences, or after receiving unexpected errors,' and a clear WHEN NOT TO USE constraint: 'Do not call more than once per minute in production.' Also gives a matching example user query, leaving no ambiguity about appropriate invocation.

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