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

Beyond the destructiveHint annotation, the description discloses critical behaviors: the status field semantics ('pending', 'confirmed', 'completed'), the deduplication behavior of clientRequestId on retries, and the warning not to misreport 'pending' as 'confirmed'. It also details the address requirement condition, adding rich behavioral context.

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 front-loaded with the core purpose and then delivers dense, high-value guidance. Every sentence addresses an essential operational detail—status handling, feature gating, address requirements, and idempotency—without redundant filler.

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 compensates by explaining return fields (reference number and status). It covers prerequisites, conditional requirements, and error-prone customer messaging. For a complex mutation tool with 9 parameters, this description is remarkably complete.

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?

Even though schema coverage is 100%, the description substantially enriches parameter semantics. It explains that clientRequestId must be generated once and reused on retries to avoid duplicate calendar events, that dateTime must come from check_availability to respect bookingStartPolicy, and that customerAddress is conditionally required.

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 function: 'Book an appointment with a local service business. Creates a booking record and adds the appointment to the business calendar.' This specific verb and resource combination distinguishes it from siblings like check_availability and send_inquiry.

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?

The description provides explicit usage conditions: 'ONLY call this if the business has booking in its enabledFeatures array.' It also instructs to use a dateTime from check_availability and specifies when to provide customerAddress, giving clear when-to-use and prerequisite guidance.

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