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

Beyond the annotations (readOnlyHint=false, openWorldHint=true), the description discloses concrete behavior: the client receives a push notification that day at 10:00 local unless reminder_time is set, the client checks the task off in the app, each call is user-confirmed by default, and an API key with app access is required.

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 opening is front-loaded with purpose, but the first two sentences are redundant ('Add a task to a client's calendar' vs 'Adds one task to a client's calendar on a date'), which is wasted space. The remaining sentences are informative enough to justify their place.

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?

With no output schema and a mutation tool, the description covers enough: side effects (notification), confirmation workflow, and auth needs. It doesn't describe the response or how success is reported, which is a minor gap but not critical here.

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 six parameters including the reminder_time default. The description's 'instructions and a reminder time' only restates fields and adds no syntax or format detail beyond the schema; 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?

The description states a specific verb and resource ('Add a task to a client's calendar') and mentions the notable fields (instructions, reminder time). It is clear what the tool does, though it doesn't explicitly contrast itself with nearby siblings like everfit_assign_program or everfit_add_client_to_autoflow.

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 gives real usage context: the per-call confirmation default, the note that it 'reaches other people' and needs a confirm, and the Cotlet API key requirement. However, it never says when to prefer this over an alternative sibling, so the when-to-use guidance stays implied.

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