unsubscribe

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

Discloses significant behavioral traits beyond annotations: 'makes an outbound HTTPS request... confirms to the sender that the address is live, and it cannot be undone.' Also explains handling of non-automatable senders and that 'the mailbox itself is not changed.' No contradiction with readOnlyHint=false, openWorldHint=true, idempotentHint=false, destructiveHint=false.

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?

Though longer than a minimal description, every sentence adds value. The use of clear sections (USE WHEN, DO NOT USE, SIDE EFFECTS) makes it easy to scan. The information is dense but well-organized, with no filler.

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?

The description covers the tool's operation, limitations, side effects, return behavior ('returns unsubscribed:false with the alternatives in `options`'), and relationships to sibling tools. For a tool with one parameter and an output schema, it is complete and anticipates user questions.

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 single parameter threadId is not explicitly defined, but the description implies it identifies the thread containing the mailing list message. It adds crucial context by explaining why there is no URL parameter: 'the endpoint is taken from the message's own List-Unsubscribe header and nowhere else.' This compensates for the 0% schema coverage.

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's function: 'Unsubscribe from the mailing list a thread came from, via the sender's RFC 8058 one-click endpoint.' It specifies the mechanism (one-click endpoint) and distinguishes from siblings by explicitly saying 'DO NOT USE: to check whether unsubscribing is possible (use list_unsubscribe — it contacts nobody).'

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?

Provides explicit usage guidance with 'USE WHEN: the user wants off a newsletter' and 'DO NOT USE' sections, including a direct alternative (list_unsubscribe). Also suggests pairing with archive/trash or create_filter, giving practical context for when to invoke this tool.

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