list_unsubscribe

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

Beyond the readOnlyHint annotation, the description discloses that no request is made to the sender, that it reads the newest message carrying the header (so replies don't hide it), and explains the meaning of oneClick, httpsUrls, and mailtos. This is substantial behavioral context.

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 with a clear function statement, special behavior, field interpretations, explicit usage guidance, and side effects. Every sentence adds value and no content is redundant with the schema or annotations.

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 simple read-only tool with one parameter and an output schema, the description covers purpose, behavior, edge cases, and usage. It is complete enough for an agent to select and invoke correctly without additional context.

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 schema provides no description for the sole parameter `threadId` (0% coverage), so the description must compensate. While it doesn't explicitly define `threadId`, the entire description revolves around 'thread' and how the tool operates on it, making the parameter's meaning clear from context.

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 the tool reports opt-out options (List-Unsubscribe / RFC 8058) without contacting anyone. It distinguishes itself from sibling tools like `unsubscribe` by explicitly noting the `unsubscribe` tool can perform the one-click opt-out.

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 includes an explicit 'USE WHEN' section: checking whether a newsletter can be unsubscribed from, or showing the user the link to click. It also contrasts with the `unsubscribe` tool for performing the opt-out, and clarifies that mailtos require human action since mailwarden never sends mail.

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