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

Annotations already cover the safety profile (readOnlyHint, destructiveHint=false, idempotentHint), so 'Read-only: it books nothing' largely reinforces them. The description still adds useful behavioral context beyond annotations: the 14-day window cap, the 7-day default, and that times come back in the requested timezone. It does not describe pagination or result volume, so it stops short of a 5.

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?

Front-loads the purpose and usage condition, with window/behavioral details following. Slightly redundant in stating read-only twice ('Read-only: it books nothing' against readOnlyHint=true) and does not state which fields drive selection before the trailing behavior notes.

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?

No output schema exists, and the description does step in to note that times are returned in the requested timezone, which is what an agent needs to interpret results. For a zero-required-parameter, read-only listing tool this is near-complete, though return shape (slot objects, count) is unaddressed.

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 schema already documents all four parameters including the date format, defaults, and timezone. The description restates the window and timezone behavior but adds no syntax or constraints beyond what the schema provides. Baseline 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?

States a specific verb (List) and resource (open slots for a 30-minute intro call with Matt Turley), and distinguishes the source (live Cal.com calendar). An agent can immediately separate this from the sibling book_call.

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?

Explicitly names when to use it ('when the user wants to talk to Matt, get help with a project, or book a call') and routes to the alternative by specifying 'before calling book_call'. Nothing is left to inference.

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