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

Annotations already declare this a safe, idempotent, closed-world read. The description adds two pieces of real value: results are constrained to a specific timezone, and 'Phase 1 uses a deterministic schedule stub' warns that returned availability is synthetic, not live — a trait no annotation conveys. The dev-facing 'Phase 1' phrasing slightly weakens it.

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?

Two short sentences with zero padding, leading with what is listed and the timezone constraint before the caveat. Every clause carries information.

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?

All three parameters are documented in the schema and an output schema exists, so the description only needs to orient the agent — which it does, resolving the timezone question and flagging the stub data. Only the missing hand-off to request_appointment keeps it from a 5.

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 days, from, and meetingType are already fully documented, including the 1-21 range and default. The description adds only the fixed timezone, which is useful context but not parameter-level meaning beyond 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?

States a specific verb and resource ('Lists open appointment slots') plus scope details: timezone America/New_York and the three supported meeting types. It doesn't explicitly name request_appointment as the booking counterpart, but the purpose is unmistakable and readably distinct from the other siblings.

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?

Implies the discovery use case by enumerating valid meeting types, but never states when to call this versus request_appointment, nor that list_open_slots is the prerequisite step before booking. Usage is inferable rather than explicit.

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