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

The annotations already declare readOnlyHint=true and destructiveHint=false, and the description explains why: the tool "opens nothing by itself" and only returns step-by-step instructions that must be executed by cotlet_browser_* tools. It also discloses that CoachingPortal has no public API, which explains the browser-delegation design. This resolves the otherwise confusing mismatch between the name "send" and a read-only annotation.

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?

Three short sentences cover what the tool is, what it returns, and how to act on the result, with the key non-obvious fact (it opens nothing) front-loaded. The closing API note ("CoachingPortal's official API: CoachingPortal publishes no public API") is slightly redundant in phrasing but earns its place as rationale.

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 parameters and no output schema, the description carries the burden of explaining the return value, and it does so broadly (step-by-step screens, buttons, fields). An agent knows enough to call it and to know what to expect back, though it is not stated whether the steps are returned as structured data or prose.

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 input schema has zero parameters, so there is nothing to disambiguate and the baseline of 4 applies. The description correctly implies no parameters are needed by describing the call as a pure instruction lookup.

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 names a specific verb and resource ("Send voice message in the user's own CoachingPortal account") and clarifies the surprising twist that the tool returns instructions rather than sending. It does not, however, distinguish this from the sibling coachingportal_send_message, so an agent must infer that voice vs. text is the dividing line.

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 an explicit execution flow: call this tool to get the step-by-step, then perform the action with cotlet_browser_* tools in the user's Cloud Browser. That is clear routing guidance. It stops short of saying when a voice message is preferred over a text one (coachingportal_send_message), so the choice between siblings 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.