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

Annotations already declare readOnly/idempotent/non-destructive/openWorld=false. The description adds genuinely new behavioral context beyond those: the 14-day and 100-slot caps, the per-day aggregation shape (count plus first start and last end), and a privacy guarantee that no pet/owner/medical data is returned.

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, zero filler, front-loaded with the usage trigger before the return shape and caps. Every clause earns its place.

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 simple one-parameter read tool with full annotation coverage and an output schema, the description supplies the remaining unknowns: result caps, aggregation granularity, privacy scope, and the non-booking boundary. Nothing an agent needs to call it correctly 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?

Only one parameter (clinicId) and schema coverage is 100%, so the schema already documents the 24-hex-char format. The description adds only the framing that the query is scoped to a single clinic, which is the baseline expectation when the schema does the heavy lifting.

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+resource (returns open online-booking slots per day for one clinic) with the scope constraint 'one clinic' and explicitly disclaims booking. An agent can distinguish it from list_calendar_events or get_clinic_schedule_summary from the description alone.

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?

Gives a clear trigger ('when someone asks when their vet clinic has free appointment slots or openings') and an explicit exclusion ('Not for booking an appointment'). It stops short of naming the sibling tool that handles the excluded case, so the agent must infer the routing.

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