List mail addresses

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

Annotations already indicate readOnlyHint=true, so the description's role is reduced. However, it adds valuable behavioral details: addresses are concrete, output modes (sender, recipients, count) are explained, and the ranking behavior for 'count' is disclosed. No contradictions with 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?

The description is well-structured: a one-line purpose, a problem-context paragraph, then parameter docs in bullet style. It is clear and mostly concise, though slightly verbose in the problem explanation. No wasted sentences.

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?

Given no output schema, the description explains what the tool returns (concrete email addresses) and mentions ranking for 'count' output. It does not specify output format (e.g., list of strings), but the context is sufficient for an AI to understand the return type. Sibling tools are listed, and the tool's role in the workflow is clear.

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?

With 0% schema coverage, the description fully explains all 4 parameters: query (name fragment), scope (with reference to mail_list_scopes), output (three modes explained), and limit (maximum count). This compensates completely for the lack of schema descriptions.

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 clearly states 'Resolve a name or query into the concrete email addresses behind it,' specifying the verb (resolve) and resource (email addresses). It distinguishes itself from siblings by focusing on address resolution, a unique function compared to mail_count, mail_list_scopes, etc.

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 explicitly advises to call this tool first when only a name is available, contrasting with unreliable direct 'from:<name>' search. It provides a clear workflow: resolve name to addresses, then use those addresses for search or count.

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