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

readOnlyHint=true already establishes the safety profile, so the description only needs supplementary context, and it delivers: the hard 31-day window cap, the product-type constraint, and the underlying Bookeo endpoint (GET /availability/slots). It stops short of describing result ordering or pagination semantics, which the schema partially covers via pageNavigationToken, so a 4 rather than a 5.

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 short sentences, zero filler: capability and scope first, the exclusion/alternative second, the API mapping last. Every sentence carries decision-relevant information and the key routing signal ('not for flexibleTime') is not buried.

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 naming the returned fields, and it covers the domain constraint (31-day cap), the supported product types, and the sibling routing. An agent has everything needed to select and call this tool correctly.

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 including the subtle 'mode=backend' manager override and the -00:00 timezone convention are already documented in the schema. The description adds no parameter-level meaning beyond the field names it lists as outputs, 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?

The description pairs a specific verb ('List available slots') with the resource, its scope ('fixed and fixedCourse products'), the window constraint, and even the returned fields (eventId, start/end, seats available). It explicitly excludes flexibleTime products and names the sibling to use instead, so the tool is distinguishable from bookeo_search_matching_slots without any schema inspection.

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?

States the positive use case (fixed/fixedCourse products in a window up to 31 days) and the explicit exclusion with a named alternative: 'Not for flexibleTime products — use bookeo_search_matching_slots for those.' This is the when/when-not/alternative pattern at full strength.

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