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

Annotations already declare a safe read (readOnlyHint=true, destructiveHint=false, openWorldHint=false), so the bar is lower, yet the description still adds real behavior: the engine applies opening hours, buffers, notice and advance limits and the outlet timezone, and off-slot holds are rejected. It also discloses a latency characteristic for wide ranges. It stops short of describing the shape or volume of the returned windows, which is the one remaining gap.

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 tight sentences, front-loaded with what is returned, then the authoritative-source rule, then the performance caveat. Every sentence carries distinct information with no restatement of the title.

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 read-only, four-parameter tool with no output schema, the description covers purpose, authoritative semantics, cross-tool constraints (slot boundaries for holds), timezone handling and cost. 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?

Schema coverage is 100%, so the baseline is 3, but the description adds meaning the schema does not: the range parameters are practically bounded (a few days, not a year) and results are per resource, tying the inputs to the expected granularity of output.

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 resource and scope: the bookable windows for a product over a date range, per resource, with what is already taken. An agent can tell this is the read-side availability query and not hub_hold_booking or hub_confirm_booking without opening a schema.

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?

Explicit when-to-use and when-not-to: quote slot times from THIS result rather than computing a grid, because a hold starting off a slot boundary is refused. It also gives a practical range limit (a few days at a time; year-wide is slow and pointless), which is concrete guidance rather than implication.

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