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

Annotations already declare readOnlyHint=true, destructiveHint=false, idempotentHint=true and openWorldHint=false, and the description reinforces this with 'opens nothing by itself,' which resolves the apparent contradiction between the name 'create' and the read-only annotation. It adds useful context about the return content (screens, buttons, fields) and about EmailOctopus API coverage. However, the API background about v2 endpoints and missing campaign APIs is not behavior of this tool and does not tell the agent about cost, rate limits or output shape.

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 description is front-loaded with the operative instruction and the follow-up browser workflow, which is good. But the final sentence about the EmailOctopus public REST API, its v2 scope and the absence of an official MCP server or campaign-sending API is tangential to creating a segment and consumes roughly half the text. Trimming that would sharpen the definition without losing anything the agent needs.

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 parameterless tool with no output schema, the description covers what is returned (step-by-step screens, buttons and fields), what the tool does not do (opens nothing), and what to call next (cotlet_browser_*). It does not mention whether the call consumes credits or requires an existing EmailOctopus connection, which are relevant prerequisites given the cotlet_balance sibling, but the core contract is complete.

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 and schema coverage is 100%, so there is nothing for the description to compensate for. Baseline 4 applies. The description does not need to explain any argument meaning.

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 (create segment in the user's EmailOctopus account) and immediately clarifies that it only returns step-by-step UI instructions rather than performing the action, which is important because the name alone would suggest a write. It differentiates itself from the cotlet_browser_* siblings by positioning itself as the preceding guidance step. The remaining ambiguity is that 'Create segment' in the name and 'returns how to do it' in the body sit in slight tension, requiring the agent to read past the first clause to understand the tool is instructional.

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?

The description gives a clear two-step workflow: call this to get the screens, buttons and fields, then execute with the cotlet_browser_* tools in the user's EmailOctopus Cloud Browser. It also states the tool opens nothing by itself, implicitly telling the agent not to expect side effects. It stops short of explaining when to prefer this over a sibling like cotlet_app_guide, so the guidance is clear but not exhaustive.

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