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

Annotations cover safety (readOnly, non-destructive). Description adds key behavioral context — results are in MT local time and capped at 21 days — plus a fallback behavior when availability isn't available. Does not mention pagination or response shape, but that's minor for a read-only list.

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?

Two tight sentences, front-loaded with what the tool returns, then the practical fallback. No 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?

Covers timezone, cap, and fallback behavior for a simple read-only tool with full param schema coverage. Could note the typical next step (request_appointment) to fully close the loop, but nothing critical is missing.

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 100%, with defaults and min/max documented in the schema. The description mentions the 21-day cap but otherwise adds nothing about parameter usage beyond the schema.

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?

Specific verb+resource: 'Open arrival windows' clearly states what is returned. Distinguishes from siblings like get_business_info and request_appointment — this retrieves available slots, not appointments or info.

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?

Adds a decision rule: 'If online availability is unavailable, ask the customer for a preferred day and time instead' — a clear fallback for when not to use the tool's output. Lacks explicit mention of the sibling request_appointment as the next step after selecting a window.

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