Busy blocks and free windows

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

With no annotations provided, the description carries the full burden of disclosing behavioral traits. It does well by explaining the treatment of free events and whole-day events, and the 31-day limit appears to be a hard constraint (likely an API limit). However, it doesn't disclose details like whether the tool requires authentication, rate limits, or how it handles time zones beyond what the zone parameter implies. The 'Free: 31 days' is ambiguous—could mean the max range is 31 days, which is useful but not fully explicit.

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 concise, three substantial sentences, and front-loads the core output ('Merged busy blocks and the free gaps inside your working hours') before diving into constraints. The sentence about free events and whole-day events is critical and placed early. The 'Free: 31 days' and 'Use conflicts for overlapping pairs' add value without bloat. It earns a 4 for being tight and informative.

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?

Given the tool has 6 parameters but only 2 required, and no output schema, the description gives enough for basic usage: date range, working hours, calendars, and time zone. It clearly communicates the core output. However, it lacks details on the output format (e.g., does it return blocks in a specific structure?), error handling, or edge cases (e.g., what if no free gaps exist). For a scheduling tool, these could be relevant for agents, but the complexity is moderate, so a 3 is fair.

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 100%, so every parameter is described in the schema. The description adds some semantics by explaining that 'free' events don't count and whole-day events block the day, which relates to the 'calendars' and 'work_start'/'work_end' parameters. However, it doesn't add detail about formats or default values beyond what the schema already provides, so the baseline of 3 is appropriate.

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: it provides merged busy blocks and free gaps within working hours over a date range. This distinguishes it from sibling tools like conflicts and events_list, though it doesn't explicitly contrast with them. The verb 'Merged' and resource 'busy blocks and free gaps' are specific enough to convey purpose.

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 explains when to use this tool: for checking busy blocks and free windows over a day range, with important exclusions (events marked free don't count, whole-day events block the day). It also gives a hint to use 'conflicts' for overlapping pairs, which is an explicit alternative suggestion. However, it doesn't cover all possible alternatives or negative use cases in depth.

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