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

Beyond the annotations, it discloses that slots are deterministic and free-busy-derived, that the top three include an LLM-written why string when includeWhy is true, and how teammate and external attendee identifiers map into each slot. It also reinforces read-only safety. It does not discuss permission or quota behavior, but the annotations already carry the safety profile.

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?

Four compact sentences front-load the purpose, then add return behavior and the safety scope. Dense but every sentence carries operational information; there is no preamble or repetition.

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 description covers the core operation and output shape for a 12-parameter read-only tool with an output schema and rich annotations. It remains incomplete on several behavioral toggles and alternatives, which matters because schema coverage is low and the parameter surface is broad.

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?

With only 33% schema description coverage across 12 parameters, the description adds important meaning for includeWhy and for attendeeUserId/externalIndex output mapping. However, it leaves rankBy strategy meanings, honorWorkingHours, honorOOOAndFocus, maxResults, and preferred/source calendar parameters largely to the schema.

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 opens with a specific verb and resource ('Propose ranked meeting time slots') and scopes it by duration, window, attendees, and ranking strategy. The closing 'Read-only — never creates an event' clearly separates it from mutating siblings such as calendar.create.

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?

It establishes the general context for proposing slots and explicitly rules out event creation, but it does not say when to choose this over calendar.prep_brief, schedule.read, or availability.create, nor does it state prerequisites. Usage is therefore implied rather than fully guided.

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