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

Annotations already declare readOnlyHint=false and destructiveHint=true, so the write nature is structured data, but the description still adds unannotated context: the new list starts empty, and the response carries id and uuid. It says nothing about permissions, duplicate-title handling, or limits, which would be the remaining behavioral gaps.

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?

A single front-loaded sentence plus a semicolon clause; the write marker, the created state, the return fields, and the follow-up tool all appear before any padding. Nothing is wasted.

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 output schema, the description usefully discloses that the result contains id and uuid, and it names the follow-up tool, which is what an agent needs to chain calls. The only meaningful hole is the total absence of parameter detail for a tool whose schema has 0% description coverage.

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?

Schema description coverage is 0%, so the description must carry parameter meaning, yet it never mentions email_list_title or email_list_description. An agent gets no guidance on title length, uniqueness, or whether description is optional from the description text.

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 ('creates an empty saved recipient list') and immediately bounds the scope by saying the list is empty, which is not obvious from the name alone. It distinguishes itself from siblings like add_email_list_members and edit_email_list by stating what state the created object is in.

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 next step ('fill it with add_email_list_members'), routing the agent to the correct follow-up tool instead of leaving it to guess. It lacks an explicit exclusion (e.g. use edit_email_list to rename an existing list), so it's strong but not complete when/when-not guidance.

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