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

Annotations already declare readOnlyHint=true, and the description adds real behavioral context beyond that: the 31-day maximum window and the product-type restriction. It also discloses the underlying endpoint, aiding predictability, though it doesn't discuss pagination behavior explicitly.

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 plus an endpoint reference; the scope and routing constraint are front-loaded and nothing is redundant. 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?

With no output schema, the description helpfully enumerates the returned fields (eventId, start/end, seats available), and the schema covers paging. It is nearly complete, though it could note response shape or paging semantics in the description itself for a list endpoint.

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%, so all seven parameters are already documented in the schema, including the paging trio and mode enum. The description reclarifies productId's scope ('fixed and fixedCourse products') but adds little beyond what the schema already states, so the baseline 3 applies.

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 (List) and resource (available slots), names the returned fields (eventId, start/end, seats available), and explicitly limits scope to fixed/fixedCourse products. It cleanly distinguishes itself from the unrelated list_* siblings and from search_matching_slots.

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 states when-not to use it ('Not for flexibleTime products') and names the alternative tool to use instead, which is exactly the routing an agent needs. The 31-day window constraint further bounds correct usage.

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