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

No annotations are provided, so the description carries the full burden. It discloses how the tool works ('using coach working windows and busy intervals') and adds a privacy guarantee ('The response never includes private learner data'). This goes beyond the basic 'search' concept and provides useful behavioral context, though it does not mention rate limits, pagination, or read-only status explicitly. For a read-only search tool, this is reasonably transparent.

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?

The description is two sentences, both front-loaded with essential information. The first sentence delivers the primary purpose, and the second provides a key privacy note. No redundant filler or fluff; every word 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?

The tool has six optional parameters and an output schema, so the description needs to explain how parameters relate to the search behavior. It does not explain the purpose of date_from/date_to, limit, or user_timezone. While the output schema covers return values, the lack of parameter guidance and absence of annotations leaves gaps for an agent trying to customize a search. The high-level purpose is clear, but the description is not fully complete for effective invocation in varied scenarios.

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 description coverage is 0% — no parameter descriptions exist. The description does not mention any of the six parameters (limit, date_to, date_from, coach_slug, service_slug, user_timezone). It only vaguely refers to 'coach working windows and busy intervals,' which hints at coach/service relevance but provides no concrete meaning for the parameters. The tool name and schema titles carry some meaning, but the description adds negligible value for parameter understanding.

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 clearly states the tool's function: 'Find free requestable lesson times using coach working windows and busy intervals.' It uses a specific verb ('Find') and resource ('free requestable lesson times'), and the method distinguishes it from sibling tools like create_lesson_request (which creates) and list_lesson_options (which lists options). It is unambiguous and immediately understood.

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?

The description implies the tool's usage context (searching for available slots) but does not explicitly state when to use it over alternatives. It does not reference sibling tools or provide exclusion criteria, such as 'Use this to check real-time availability, as opposed to list_lesson_options which gives fixed offerings.' Thus, the usage guidance is only implicit, not explicit.

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