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

Annotations already declare readOnlyHint=true and that nothing external is opened; the description reinforces this with 'opens nothing by itself', so there is no contradiction and the agent gets confirmation that invoking it has no side effects. It also discloses what is returned (screens, buttons, fields). It does not cover anything further such as how current status is discovered, but with annotations carrying the safety profile this is adequate.

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 key point, that this only returns instructions, is front-loaded in the first two sentences with no wasted wording there. The trailing sentence about Mailshake's REST API and lack of an official MCP server is background justification rather than call-relevant instruction, so it is slightly overlong.

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, no-output-schema tool, the description covers what it returns and how to act on the result, which is what an agent needs to sequence the browser tools. The only shortfall is that it doesn't say whether the guide is specific to a named lead or generic, though with no parameters it can only be generic.

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 the baseline is 4. The description correctly implies no input is needed and focuses instead on what the caller must do afterwards, which is the relevant semantic information for a no-arg tool.

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 specific resource and action (lead status in Mailshake) and, crucially, what the tool actually produces: step-by-step instructions with screens, buttons and fields. It also clarifies the tool does not perform the change, which sharply distinguishes it from acting siblings like mailshake_move_leads_to_another_campaign.

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?

Guidance is explicit about the workflow: call this to get the steps, then execute with cotlet_browser_* tools in the user's Mailshake Cloud Browser. It gives a clear context for use. What it doesn't do is name an alternative path when a direct API-style sibling exists, so it stops short of a full when/when-not statement.

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