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

Adds substantial context beyond annotations: it won't touch existing appointments, it creates one block not a repeating one, it confirms each call by default (switchable), the user must confirm before calls since it reaches other people, and it needs an API key with app access. This is exactly the side-effect and auth disclosure annotations don't provide.

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-loaded with the core action, but the first two sentences restate the same idea ('clients cannot book you then' / 'clients cannot book you online during it'), which is wasted space. The remaining sentences each earn their place, but the redundancy drags it below a 4.

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?

For a mutation tool with no output schema it covers the important ground: side effects, non-repeating scope, prerequisite list, confirmation default, and auth requirement. Minor gaps remain (no return confirmation detail, no note on overlap/conflict handling), keeping it short of 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 description coverage is 100%, so start/end/description/provider_id are already documented in the schema. The description adds no parameter-level detail (e.g., timezone format or provider defaulting), so the baseline 3 applies.

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 ('Add a personal time block') and immediately explains the effect ('clients cannot book you then'). It distinguishes itself from siblings by referencing list_appointments as a separate pre-step, so an agent can tell it apart from book_appointment or find_open_slots.

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?

Gives clear context (block personal time so clients can't book) and an explicit prerequisite ('run list_appointments for the same range first'). It does not name a when-not-to-use condition or a true alternative tool for blocking time, so it stops short of full routing guidance.

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