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

Annotations declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds valuable behavioral context: the returned slot structure (start, end, readable label), the 30-minute weekday timezone constraint, and the critical caveat that a slot is not a booking and requires confirmation via create_booking_link.

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?

Three tightly packed sentences: first states scope and return shape, second states the crucial non-booking caveat, third hands off to the sibling. Zero waste, front-loaded.

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?

Complete for a read-only availability checker with annotations covering safety and a description covering return shape, constraints, and the booking handoff. No output schema, but the description summarizes what's returned. Slight gap: pagination/empty-result behavior is not addressed, but not critical here.

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% with clear descriptions for daysAhead (default 7, max 30) and durationMinutes (default 30, range 15-120). The description mentions the 30-minute default but doesn't add syntax beyond what the schema provides, 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?

States a specific verb (returns slots) and resource (agency's appointment calendar open slots), with scope constraints (30-minute meetings, weekdays, agency timezone). Clearly distinct from create_booking_link, which is named as the next step.

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?

Explicitly tells the agent what this tool is for (real open slots) and what it is not (a booking), and names the alternative/successor tool (create_booking_link) with the condition for using it. No ambiguity about when to invoke.

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