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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is covered. The description adds real value by confirming it 'opens nothing by itself' and returns guidance text rather than taking action, which is the single most important behavioral fact given the misleading 'send' naming. It says nothing about prerequisites (an open Cloud Browser session, logged-in account) needed for the suggested follow-up to succeed.

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 actionable content (returns step-by-step guidance; nothing is opened; continue with cotlet_browser_*) is front-loaded and clear. The trailing sentence about Aircall's public REST API and beta MCP server adds no decision-relevant information for invoking this tool and dilutes focus.

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 guidance tool with no output schema and full annotation coverage, the description supplies everything an agent needs: what it returns, that it performs no action, and which tools to chain next. Nothing needed for correct invocation is missing.

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?

There are zero parameters, so the baseline is 4 and no parameter explanation is required. The description correctly implies no inputs are needed to obtain the guidance.

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 the domain task (SMS in Aircall) and clarifies the actual mechanism: it returns step-by-step screens/buttons/fields rather than performing the send. The opening sentence 'Send SMS in the user's own Aircall account' momentarily reads like the tool itself sends, but the second sentence resolves that. It is distinguishable from siblings by explicitly naming cotlet_browser_* as the action layer.

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 tells the agent the follow-up path clearly: call this, then use the cotlet_browser_* tools in the Aircall Cloud Browser to actually execute. It gives no explicit 'when not to use' or comparison to other aircall_* siblings, though SMS is a unique capability among them so the risk of misrouting is low.

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