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

Beyond the readOnly/idempotent annotations, the description discloses the crucial behavior that this call has no side effects on the Sendible account ('opens nothing by itself') and that its payload is procedural guidance (screens, buttons, fields). It also explains why browser automation is required by noting Sendible documents no public API, which is genuine behavioral context not present in the annotations.

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?

Two compact sentences carry the key distinctions up front (guide-not-action, then browser tools), with no redundant restatement of the title. The trailing API note about a checked date is slightly awkward but earns its place by justifying the browser-based approach.

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 must explain what comes back, and it does: step-by-step UI instructions rather than report data. It leaves unstated what the engagement report covers (metrics, date ranges) and how the guide is scoped without any input parameters, which is a modest gap for a zero-parameter tool.

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 schema has zero parameters, so there is nothing for the description to disambiguate; the baseline for a 0-param tool applies. The description correctly implies no inputs are needed before running the browser workflow.

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 (get engagement report) and then immediately clarifies the non-obvious twist: it returns step-by-step UI instructions rather than the report data itself. That distinction separates it from data-returning siblings, though the opening phrase 'Get engagement report' could momentarily suggest a data fetch before the second sentence corrects it.

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 clear workflow context: this tool opens nothing by itself, and the actual operation must be performed with the cotlet_browser_* tools in the user's Cloud Browser. It does not explicitly name an alternative like cotlet_app_guide or state when-not to use it, but the sequencing guidance is concrete enough for an agent to act on.

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