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

Annotations already declare readOnlyHint=true, idempotentHint=true and openWorldHint=false, and the description is consistent with all of them. Beyond the annotations it discloses the concrete return shape (screens, buttons, fields) and the critical fact that no browser session is opened as a side effect, which an agent could not infer from the flags alone.

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 first sentence is front-loaded and useful, but the phrasing is repetitive ('Send secure message... Returns how to do it... opens nothing by itself') and the API note is grafted on as a trailing fragment with an oddly specific date. It is readable but not tight.

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 zero-parameter, read-only guide tool with no output schema, the description covers what the agent needs: what it returns, that it performs no action, and which sibling tools complete the workflow. Return-value detail is necessarily summarized rather than structured, which is acceptable 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?

The tool takes zero parameters, so there is no schema semantics to supplement and the baseline of 4 applies. The description correctly implies the only variable input is implicit user context (the user's own account), with no additional arguments needed.

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 ('Send secure message in the user's own SimplePractice account') but immediately reframes it: the tool actually 'Returns how to do it in SimplePractice step by step' rather than performing the send. That reframing is essential and clearly stated, though the mismatch between the action-oriented name and the guide-only behavior costs a point.

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 explicit sequencing: read the returned steps, then execute them with the cotlet_browser_* tools in the user's Cloud Browser, and notes that nothing is opened automatically. It also justifies the approach by stating SimplePractice has no public practice API. It does not distinguish itself from cotlet_app_guide or similar guide siblings, which keeps it below a 5.

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